Processor compatabilty

I am having a hard time figure out what processors are compatible with my system. I have been trying to look up the compatibility through my mother board but have been having a really hard time with it. I currently have an AMD Phoenom 9550 and would like to upgrade to something better, although I think I'm going to be pretty limited due to my computers DDR 2 RAM. What are my options for a better processor/how do I go about finding out? I have tried googling Pegatron and Pegatron Violet 3.02 but I haven't gotten any luck

System specs:
2.20 gigahertz AMD Phenom 9550 Quad-Core
512 kilobyte primary memory cache
2048 kilobyte secondary memory cache
2048 kilobyte tertiary memory cache
64-bit ready
Multi-core (4 total)
Not hyper-threaded

Board: PEGATRON CORPORATION VIOLET 3.02
Serial Number: MS1C94R42401143
Bus Clock: 200 megahertz
BIOS: American Megatrends Inc. 5.08 02/03/2009

and I have 8GB of DDR2 RAM

Yeah after some googleing Pegatron seems to be a branch of Asus dedicated to motherboards... and I've been having a very hard time figuring out what I could possibly upgrade to. If it helps the computer is an HP that I bought a new case a 260GTX and a new power supply. But as far as a possible upgrade list I can't find anything anywhere

so you think it will work??

It seems like AMD puts out a new processor or new revision almost everyday. Chances are that you won't be able to upgrade that Processor unless there's a new BIOS update to support the newer processors. Phenom 9950 is probably your best bet of compatibility, but that's only a 400Mhz gain, which is totally not worth it.

That's what you get when you buy retail PCs.

If you've already bought a new case, psu, and graphics card.......then just get a new motherboard/ram/cpu to complete your new computer. You can probably get all three for under $250 if you go AM3. If you go AM2+, then you can reuse your ram and save like $80.

Oh yea, missed that part. No 140W CPUs.
Never buy a 140W CPU from AMD. Only a handful of motherboards support them.

I got the same mother board. I have a AMD Athlon II x4 620, and it is not on the list either. I bought my PC with that processor in it, so I don't think the list on the HP website is exclusive.