What is W32/Agent?

I am running win98 and my Command Antivirus software detects W32/Agent.CY@dl, .GQ@bd and .l@dl, as well as 32/Downloader.lA and .lb every time I reboot the machine. It says these are deleted, yet they reappear each time. Norton Antivirus doesn’t detect them, nor do any of the numerous anti-spyware programs I have used. What virus is this and how do I get rid of it?