If you don't mind going on eBay then you may want to get an ATI X1900 or nvidia 7900 series AGP card. Of course those cards are a bit power hungry so make sure you have a decent PSU. Overclocking your CPU would certainly help to make things playable. If you have a Barton Athlon 2600+ (I think there was also a thorton, ie 256k cache disabled) then you should be able to overclock it a bit. If it's the Thoroughbred, not so much.
I wish to thank all those who replyed. I will look into the suggested Graphic cards. If there is any thing else like driver I should know about please let me know. Again many thank for your kind replies.