I think i have a computer virus?

my computer is a dell xp, Ad-aware and pc cillen internet security arent fixing the problem and everything is running slow and taking forever to open , and there is alot of popups, and there is this code that keeps popping up that says C:/windowsystem321fccabcd.dll, does anyone know what is wrong with my computer and know how to fix it , please give me step by step in how to fix it , thanx help appreiated

I think i have a computer virus?free antivirus download

It sounds like you have Trojans:

No antivirus or antispyware protection is perfect, not even the expensive ones but a good mixture will help you clean your system and hopefully keep it clean. It is advisable not to run two or more anti virus applications.

For starters, download, update and run a full scan using the following product:

http://www.superantispyware.com/

SuperAntiSpyware is exceptional and will remove the majority of difficult Trojans and Worms, not just the easy ones.

If possible it is recommended that you load the application in normal mode but run it in Safe Mode. Safe Mode can be started by continually pressing F8 during the boot sequence. However, if you are badly infected you might need to run SuperAntiSpyware more than once to help clean your system. If the only infections now being shown are in System Restore, once you are completely satisfied that you can boot normally, you can either delete the infected restore points manually, or temporarily turn off System Restore.