I BIT TOO LONG BUT MAY BE WORTH IT.
I just finished restoring a 2 year old pc for a friends business.
The computer was running so bad that instead of just cleanin it I decided to do a clean install from the hidden partition. Now I am not recomending you do this first. Try changing the channnel as other mentioned and making sure you have no phones running in the 2.4 gigahertz that your router is running on, near the router as this may create interference with your router.
The reason why I am gettin involved in this discussion is to help you first and second because I just finish experiencing the same issue with this restoration. But I had it too with other computer in the family running XP.
1-Before you do any of what I am about to discuss, you should create a restore point and have the original drivers you had when you purchase your USB Wireless ready maybe on a thumb drive, downloading them from the manufacturer of your USB wifi.
2-Create a restore point by clicking the start orb, place your mouse over the install applications, go to Advance Options, then System Tools and click on Restore Point. Make sure the restore point succeded and close the window.
3-The following must be done at your own risk, but I most tell you that this is how I have fix the same problems. Specially in your post you indicated that you are a non techie.
- A little bit of background - You mentioned that when you run a cat 5 cable from the router to your pc, that everything works fine. Because the Ethernet controller drivers almost never change, the settings on the register are almost always the same, unless something like an updated driver downloaded from XP update, updates the settings, but because it is consider a STATIC Ethernet Card, it is easy for the pc to connect to the internet via the Ethernet Card and gets a bit tricky when doing it via wi-fi.
This aslo brings me to the point that - We don't know if you have updated your USB wi-fi drivers, AND how many times you have done it.
Updating drivers for Wi-fi, can create the problem you are experiencing, such as I have found out through trial and error.
Uninstalling the drivers from the control panel, hardware tab, does not necessarily fix the problem, because XP keeps folders of hardware install drivers, so as soon as you re-boot the pc, XP will look into those folders, install the drivers found and recreate the conflict.
The only way I have found to STOP XP from loading the same drivers from the folders is by doing a little tweking in the Register. This will give you the ability to start fresh and install the original drivers without any possible changes that may have occur to them or the XP Wireless Zero Configuration manager via an XP patch or a possible update to the USB drivers via Windows Update.
-Another possible situation is that - your wifi usb came with the drivers and application to handle the connection. The software that remembers your password and settings for your router is loaded at startup with windows. However, windows also has its own wifi manager to handle the connection to the router. If for some reason, there is a change on which application handles the wifi connection, this could give you messages such as the one's you are describing, Because there are 2 applications fighting to connect to the router.
-When you install the drivers for the usb, it may have given you the option to use - either the applications that came with the usb or the wifi zero configuration manager that is implemented in windows. If you choose to allow your usb application and then change it to allow windows to manage the connection. The application for the usb is still being loaded at startup and that can create a conflict since two applications are trying to gain access to the router. I have seen this happen, and the internet connection just goes on in circles because you can only have one application managing your connection to the router. After a while it picks one and connects but this a possible explanation for the intermitent connections your are experiencing.
- So that you know - Everytime the Wifi drivers are deleted, the pc rebooted and windows installs the drivers, it creates a new folder in the register. for Example.
-The first installation of the wifi drivers would be named " Wireless Network Connection".
-In removing drivers and rebooting the pc, windows creates a new folder but this time names the connection - Wireless Network Connection 1 " then 2 if you repeat the process, and XP will do this so long as you are trying to fix the problems by repeating the uninstall/install process.
-All of this folders have connections settings, but windows will go throu them until it finds the folder with the appropriate settings.
It will connect but since it has different folders in the register it can also cause a conflict.
-So here is where my help comes in.
1-Revoved the driverss to your wifi usb in the control panel - DO NOT REBOOT THE PC and REMOVE YOUR USB WIFI.
2-Remeber the changes I am about to recommend will be reversed if you did your restore point properly, so don't be too concern, but again it is at your own risk.
3-Click on the Start Orb - Select Run - Type RegEdit.
4-The Register windows will appear.
5-At the top of the register in the menu bar - Select Edit - Select FIND.
6-In the box that appears type Exactly this no quotes - "Wireless Network Connection".
7-DO NOT DESELECT ANY OF THE CHECK MARKS.
8-Press Find Next.
The system will begin searching for that exact phrase. Be patient, it may take a while.
When the first entry is found. Pay attention to this.
The entry will be located insice a folder named Connection (in English) this is the sub-folder - The master folder will be just above this one and is in numerical form.
You must delete the master which inturn will delete the sub label Connections which contains the actual settings.
If by curiosity you look at the Numerical Master, you will see no entries there. It is just the way windows assings a numerical master folder for tracking purposes for the entire os.
We are not done yet.
9- Now that you deleted the first numerical master and sub, you must go back to the toolbar - click edit - click find next.
You most repeat this process, until you get the message from Windows indicating that Searching the register has completed.
-Now I mentioned to you the creation of different folders for everytime you try to uninstall/install the drivers.
so now you most continue doing searches but you will change the search string to (no quotes) " Wireless Network Connection 2 ".
If you find entries continue with Wireless Network Connection 3 - until the search goes through the entire register and comes back with Zero results.
That is the process of cleaning the register from all this wireless connection entries. I KNOW IT SOUNDS hard is not if you do it slowly and carefully.
There is no Register Cleaner in the market that would make the process easier because this are windows register folders and those are not clean as they are not consider safe to clean.
Once you finish and don't find any more entries for Wireless Network Connection, 2,3,4 and so on, now you can reboot your pc.
You will get the message that windows have found new hardware and ask you permission to look for drivers. Cancel this and install your original drivers from your thumbdrive or were ever else you put them.
Finish the installation, there should be a wizard to help you finish the installation, decide if you want windows or yor usb application to manage the connection. Follow the wizard accordingly.
Rember - if you choose Windows to manage your connection, you most make sure that the wizard application that came with your usb do not auto start with windows.
To do this, you can click on the start orb, click run - type msconfig - look at the startup TAB and deselect the usb application.
Restart your computer and you hopefully will be find from here.
Obviously, if you choose to let the usb application manage your connection you don't have to do the above step.
I am sorry that is was very lenghly, I apologize for Grammar Erros and typing and hope that you find a solution to your problem.