You could mount a cpu fan onto the card somehow. But what you should really do is look into some aftermarket fans/coolers made for the radeon 9800. There's a large selection available Here
Just look for one that fits your budget, and that lists the radeon 9800 as compatible. I'm not an expert on VGA cooling by any means, but you should be able to take any of these generic fans and attach it to the card, or replace the heatsink.