Recommend a good cpu fan for this pc?

bump!

Wow nice to see people still using the P4. The should be a LGA 775 chipset, I'm still using stock heatsink and it runs quiet so I never bothered looking for an aftermarket cpu heatsink. Lucky for you.. that's supported in majority of heatsinks. The usual favorite is:

Cooler Master Hyper 212+ $28 120 x 79.7 x 158.5 mm (L x W x H)
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Make sure you measure before you buy. My motherboard is a little higher than most and some of the bigger 120mm heatsinks don't fit. Measurements should be provided. I recently bought the following model and it works well on an i5-2500K:

http://www.newegg.com/Product/Product.aspx?Item=N82E16835233081

The coolermaster recommended by wintermint is very good, though.

Frostytech makes a list of top heatsinks by noise and cooling if you need to bust out the big guys:

http://www.frostytech.com/top5heatsinks.cfm