I don't mean to diss you just to inform you. You haven't looked up any info on your PC have you? A socket 939 is an AM2 socket and it is still very much being made. Also there are tons of CPU fans that will work for your system on Tigerdirect.com. Any AM2 socket will work fine.
I have the
http://www.tigerdirect.com/applicati...p?Sku=ULT40030 and it keeps my AMD Athlon X2 5000+ CPU cores under 80F most of the time.