Windows XP forum: Re-Installation Boot Loop

I am an intermediate user, but I think I'm in over my head here I am running a:
~4 year old PC, HP Pavillion desktop a1610n
Windows XP MCE 2005
AMD athlon 64 processer - dual core
2 x 512MB ram sticks
etc.
I am trying to reinstall windows, and because I never got a setup disk, am using the WINNT32.exe application in the C:\WINDOWS\system32\I386 folder. It was running fine, then rebooted the computer halfway through. Ever since the program did this, it is stuck on the third step, and the progress bar for installing devices moves a bit every once in a while, but ultimately it just blacks out and reboots. Repeating this procedure (ad nausea) I now cannot enter windows XP. If I try to turn it on, then after the windows XP black loading screen, just opens up a blue screen saying "Windows setup is resuming.............." When I tried Safe Mode, I was able to log in, but before the system would even consider thinking about sparing me by loading the taskbar, I get a Windows XP Setup message, saying it can't complete in safe mode. The Computer will now restart normally. Also, I noticed that it seems it's trying to install Professional where I have Media Center pre-installed. Worst case scenario, if required, I can borrow the XP Professional disk from my neighbour. As this is my first forum post (and the fact I'm only 13), if you could keep the instructions fairly techy but also not too sophisticated that I can't understand them. I am really ticked, and my dad & brother are too, as I have to use their computers!
Thank you so much in advance,
Warren