I'm assuming CVS only for now?
AFAIK, it will be cvs only for a long time - it is just the working ground of Princec - he uses that libary to develop his commercial offerings. I don't think he will be doing spgl releases any time soon, as he is busy getting Alien Flux done.
but do I need anything else?
Nope - lwjgl is enough to get you started - you don't even have to use spgl. Infact I'd recommend learning lwjgl first, and then when you're ready for a full blown game - take a peek at the entire spgl package. Ofcourse bits and pieces of spgl can be used without using the whole package...
I do have VC++6.0 laying around
You won't need that, unless you're going to compile lwjgl - and thats a whole other story, since it has its own dependencies.
Also, just installed Eclipse 2.1. Anything special to do for getting to work well?
I develop on lwjgl, so I just have the project included... but you should be able to just add the jar? (Project -> properties -> Java Build Path -> Libraries)