Well... I have been using LW for awhile but i have been a slow person because i did NOT have anti-virus software

Normally, i am a very cautious downloader and only download some random mp3 files, but just recently, I was looking for some free iPod games on limewire to d\l. Normally i do not go into the whole "programs" section since i dont have any antivirus software, but i was desperate for some games so i went and d\l a file. It was a .zip file so i opened it. It had a "setup.exe." file in it. I immediatly deleted that file since I din't like the look and sound of the name. I downloaded 2 more files hoping to get a game. Both of them had "Setup.exe" files contained in a .zip file. Me not knowing about iPod games and their formats, opened one of the files. I belive it said something about the file having corrupted data and i closed out of it. I deleted the file and decided not to download anything else.

This was all about a week ago. Now my computer is acting pretty strange. Here are some things i am experiencing:

1) Constant 0 Disk space on my D: drive.
2) Windows task manager will not open.
3) Just recently, my firefox browser has been acting strange(wierd structure).
4) Limewire won't uninstall(corrupt files wont let it)

I am 99.99% sure i have a virus on my computer that is causing this problem. The only problem is I can't install AVG anti-virus on my D: drive because it constantly has 0 disk space. My computer is set to install files to the D: drive and not my C: drive(has a ton more space).

So my question is:

Can anyone here help me with change the install location of the files from my D: drive to my C: drive? (I have windows xp)

PS: If you need any more information, i'll try to get it to you.