EggXpert

I have a computer that has Windows 2000 and had a worm infect it and now can not be rebooted. I already have a new monitor and key board so really just need the tower with hard drive and memory-is that something I can buy seperately from a whole new system or is it better to just bite the bullet and get a new complete computer?

You should be able to take the Windows 2000 installation disk, delete the partition during reinstallation, create a new one, format it, and install windows 2000 onto it, that'll wipe out all of the data on the computer, so make sure you back up your files.

yep, no reason to rebuild unless there is a hardware failure.  just reboot as SergieV said.

Might be a good idea to start another computer (go to a friend's house or something) in safe mode and plug this HDD in there to retrieve your data

You can plug out your hard disk and install it into a computer with antivirus software. Then scan and disinfect your hard disk. After that reinstall it into your computer, then login your windows and install a antivirus software.