MAJOR Computer virus. XP disk not working....

Hello,
About a year or so ago, my desktop computer (Windows XP) got infected with tons of viruses out of nowhere (Well actually my virus program stopped updating (I had McAfee which is bad in the first place)). The computer then got to the point where it takes the computer four hours to start, and that I can't log on my account, or any account for that matter. I told my friend about my problem and he gave me the installer for AVG free. No luck. I then bought a windows xp disk and and then when I started it up, the disk drive REFUSED to open. And this is when I came to you. Is there a virus scan that can scan external system volumes when plugged via Ethernet? If there isn't, what do I do either to get my cd drive to open or, to get me to log on my account (and remember a boot disk won't work, and I also have to get on an account to run a virus scan).