Little help here, from the AMD hardcore peeps here

I am thinking of using a Heatsink for a p3 on my XP1900. Think it will take?? its a Alpha Pal6something with a 5000 rpm fan. Any ideas would help

Sounds like an Alpha PAL 6035. It would be very marginal. at best, and only with a 38 cfm Delta screamer at that. You might get away with it for a while, but go ahead and invest in a good hsf, like the Thermalright SK6, the Alpha PAL 8045 or the Swiftech MCX462. They will cool it properly and you should have no problems with cooling with any of these 3 heatsinks.

The Alpha PAL-6035 isn't up to the task-at all. Nor is an Alpha PEP-66.
The Swiftech MCX462 is the king daddy of HSF's for Athlon XP's. But it's quite expensive. The Alpha PAL 8045 is 95% as good as the Swiftech, for a lot less moolah. This presupposes that a Delta 69 cfm 80mm is on both of them. Make sure that these HSF's will fit your mainboard before buying!

The Thermalright SK-6(there are different models, get the one that's heaviest) will do fine. If you want to go cheap, a Vantec CCK-6035 with a Delta 38--or a more powerful 40-50 cfm 60mm fan will be OK. As long as you're NOT OCing.

If all that noise would drive you nuts, you can go with a Glaciator II. It performs a little worse than the MCX462 but with a whole lot less noise. Good luck in your search.