I would look at a C series for sure.....Prices are quite low, and I think u will get more from a C series Virus.
Im not too familiar with the B series, but I think the classic does not come with the Mini-Moog analogue filters, which absolutely rock!
I would say get a C series, but u may find that the Classic is sufficient for what you want to do.
Good luck with your choice, and remember, any Virus is better than No Virus
Cheers,
Jase