Oops =) I thought you meant a whole new motherboard cpu and cooler. Make sure your socket is REALLY LGA 775... here:
http://www.tigerdirect.ca/applications/SearchTools/item-details.asp?EdpNo=1187029&CatId=1588
63.5CFM!!! Cheap too! Ultra! coppper core to help heat transfer!
I'm sure theres steps on installing a LGA 775 heatsink, I will look on Google...
http://www.buypcw.com/Buypcw/specs/775CPU.htm
hmm this site says you just PRESS it in... cool.