Yah, one of the problems with having an obsolete card is that the rest of the PC probably matches it. So if you are going to throw any sort of money at it, you would be better of upgrading the whole system.
Which is something you'll probably be forced to do since most of the newer games all seem to have to have the same requirements as BW2 . If you are unable to upgrade the system, keep an eye on the Electronic stores like Best Buy, they should have regular specials on certain low end video cards for around $50. You won't be able to see fur or blooming , but they are able to play the game.