Feasible - Yes -- Security will be your responsibility

I intend to keep my XP running, however, it is my 'backup' in the event that my laptop (Vista) has problems. My laptop hard drive crashed, and I used my XP for a year. Cash kept me from getting a new drive, and then I had to reload Windows (Vista), reapply all the updates, reload all my applications -- on a part time basis took me about 3 weeks. If you continue to use for the internet (I usually don't), NEVER open an email, or file that you are not sure about. I also have some utilities that assist me keeping the hard drive well organized, and the registry clean (excess registry entries slow system speed down). I keep my XP, because I not only have old files on 3.5 inch floppies, I even have some data on 5.25 inch floppies! If and when I am able to get all my old data transferred from the XP machine, and my 98 machine, then I will consider getting rid of my 10 year old XP. Be aware that when you do upgrade to a new machine and Windows version, some older applications, that you may really like, may not work on the new machine. Some of my XP applications work well on Vista, and others (probably originally designed for 95 and 98) will not even install on Vista. A newer computer and operating system will most likely be more reliable, run faster, and will definitely be more secure. (NOTE: I'm a retired monster IBM computer programmer/analyst, and started using a PC in 1986 using DOS. I'm not a 'tech' but I learned many of the basics. TWO GOOD RULES: BACKUP, backup, backup AND WHEN IN DOUBT-- DON'T. Also, keep all of your application CDs so if you do have hard drive failure, you can restore. I have an external USB hard drive that I use for backups. If you have an older printer, I found a cable that plugs into the old printer connection and connects to a USB port on my laptop. We have internet with our cable TV company, have the internet modem hooked to a WiFi router -- use a portable WiFi USB to connect. Four PCs, and 4 smart phones all connect through that router. No connect cords. Best of luck -- if you decide to upgrade, Windows 7 isn't hard to learn. I don't recommend Windows 8 until all the 'quirks' get fixed, though.