I agree that CD daily backup or whatever interval one chooses is the best way to do backups because it removes the possibility of virus getting access to them. If one experienced an attack then the worst is just losing one day worth of files. Roel, thanks for that advice- I will start doing it immediately.

Can the virus penetrate a compressed file/zip files ?

I do my backups on the 2nd HD for at least 2-3 days backtrack (maybe should be a week but some files are very large like my pst file for outlook). And they are in zip files.