I currently have AMD 64x2 5200+ and I was wandering what I could upgrade that with? I was looking at a AMD Phenom II X4 965 but didn't know if it would work.
Take a look at this
http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01077676&lc=en&cc=us&dlc=en&product=3436817&lang=en#
Check "CPU/Processor" section.