Can 10.3.9 even fit on a 6GB HD? I wouldn't risk the upgrade unless you have the original OS disks handy.
Only one thing to do: fire up bootcamp and the Battlefield 3 beta. Let us know what kind of performance you're seeing.
Wow! That was my first mac. good times... until the hard drive crashed 2 days after I got the thing.
Anyway, upgrade it to OS X 10.1 minimum if you want to do any web browsing. I had mine on 10.1 and it ran great, so performance shouldn't be bad at all, depending on the amount of ram you have.
I don't know. It runs too well to make it a home for fish.
Should I just leave it on 8.6, or upgrade to the maximum pre-OS X software? Are there funky classic games I can use on it? How might one connect to a modern university network – should I reach out to the tech services people or just leave it off the grid?