Removing virus from command prompt

[abby1212]

Windows XP boots to desktop but locks up when clicking START button and i cannot
run explorer to access file system. Suspect a virus/malware/spyware infected. I can boot
to command prompt however. Able to recover most of my files to external drive.

Can I run an virus cleaning program while at the command prompt ? What program
should I use/buy?

Thanks

OS is XP
HW is Lenovo Thinkpad T61p