Thanx Conan. The answer I was dreading but expecting (being a cheapskate). The thing came with SIS and I've had no need to get anything posher (it's only a 256meg AMD1200 anyway. The screen is worth a lot more than the main box).
I have been thinking about investing in something new anyway (the basic problem is I only use it for internet access and typing the occasional document and it's fine for that normally. As for using it as a gaming maching I do regularly. In fact the kids have just got me to upgrade from Solitaire to Minesweeper).