If you do get a new card get a Geforce 3 or 4. These can always be transported to another system when the time comes. If you have the money, start building a new system. Not only is it fun to do but you get great experience from building systems. Go to local computer shows from time to time to get some of the best deals on parts. I buy parts at random times and before I know it I have a whole system staring me in the face.
<font color=red>When overclocking always be sure to wear clean underwear!</font color=red>