Tell me if I’m doing enough to protect my system from viruses?

I have a new PC at home, running Windows XP. I don’t do any direct file sharing from home because it’s dial-up and too slow for practicality. I use Limewire from my work computer, which is a MAC, running OS X and a broadband internet connection. Typically, I’ll download from work during off hours, unzip files there and burn them to CDs. I take them home and scan the CDs with Norton AntiVirus first, and don’t load anything suspicious.

I also run the virus scan on the PC every couple of days, depending on how often I transfer files from work.

I haven’t had any problems so far. But am I doing enough? Or are other measures called for? Can Norton see sufficiently deep into CD files to avoid trouble?

Any input would be greatly appreciated!