When he says upgrade he means go out and buy a newer card, take out your old one and replace it with the new one. That might be a little too complex for you (no offense) and since that card is so old, you might be better off buying a cheap computer that can play sins. Fact of the matter is, if your PC is really old, then those old parts won't be compatable with new parts 
So you have to ether buy a new card and install it or get a new computer. Or deal with the one you have
Sorry man