I was tied down with some computers here. Anyway, there should be no problem switching out, the only thing that comes to mind is if you have WinXP OS. It might not load as too many changes were made but the good news is if you do according to the EULA, you can install the OS in a new computer as long as you remove the OS from the other computer.
I would address the "has a couple of viruses I can't shake" issue first. Please list them out and lets see if we can not get them removed first. Do not "Ghost" if you have a known virus as you will keep it.
Go to housecall and do an on-line scan.
After the scan if it gives you results that any problems detected cannot be removed, this is what I need for you to post.
BTW, DO NOT FLASH THE BIOS. It could destroy the computer and there is nothing that can make it work.