Your motherboard is socket AM2+, and according to info here: http://bizsupport1.austin.hp.com/bizsupport/TechSupport/Document.jsp?objectID=c01357175
This board only supports Phenom processors up to 89 watts. I dont even know where you would buy a Phenom..maybe used on Ebay, but you would end up with something only slightly better than you have now.
It looks like it's time to build a new pc. You have a head start though. You can reuse your current powersupply, video card, hard drive, and optical drive.. possibly the case. Looks like a pretty standard Matx board, so you will need a motherboard, cpu, and ram. There are a lot of options, but all is determined by your budget.