Just a side note - If you get PC Gamer magazine (I know how much more mainstream can you get). They have an interesting article this month on upgrades. They compare results using a rather old Pentium II 233 system and trying various combinations of upgrades of video cards, memory, and CPU/motherboard.
One of their conclusions was that you could get a significant jump in performace with a video card upgrade even on a lower end system - since you are using a Pentium III processor with an OK clockspeed and adequate memory - you might want to look at the video card upgrade first.
This may buy you a year or so before you are forced to upgrade your processor/mbd.
I run morrowind on a Athlon 850 with 256 meg of SDram and a Geforce 2 and get very good framerates with medium detail settings.
I could go on all day...signing off for now...
Sincerely,
The Nvidia Mafia
