Here are a couple good links if you're needing to get access to SourceForge's CVS system. I haven't found any plugins which interface CVS to Visual Studio, but there are a couple good workarounds.
Haacked uses TortoiseCVS for his interface. (via James)
SourceForge's Survival Kit and their Introduction to CVS Services are great helpers too. SF's examples use WinCVS which is a somewhat confusing, overly complex interface to CVS. Hmmm... CVS often seems somewhat confusing and overly complex, so it's actually a good pairing.
It's been a couple years since I used CVS. It certainly takes a bit of getting used to again.