Upgrading 2yrs old rig - Need suggestions

Post your Mobo, however, its highly unlikely your mobo will support the x4 9950BE because it's a 140w Processor. There is a fair chance it may literally melt you Mobo if you even try it.

You would need to check to see if updated BIOS patches have been released to allow support for any Phenom. Technically they will fit your socket, but w/o a BIOS update they will not work. Many older boards were not upaded with Phenom support. Board manufacturers simply are more motivated to not do this, so they can sell new boards instead of adding support features to old boards.

Well going by this

http://global.msi.com.tw/index.php [...] _no=1#menu

It looks like your board supports 125w CPUs. You should go with a 6400+ for now and save some money. You'll get a pretty big increase. Check out the Q1 charts here. I don't think your board would melt with a Phenom, but it probably won't post. They are still updating the BIOS on the board, since it supports the new Brisbane 6000+, so I'm wondering if they don't want to support the Phenom simply to sell you a new board. ASUS has a similar board and it supports Phenoms up to the 9750, though with a lowed HT connection and no Cool n Quiet Support. Could be MSI didn't feel it was worth it since people might complain that they ain't getting all their features, while ASUS is more like "stfu, don't complain to me if you don't get it n00b. Your lucky I gave you support at all" . Yeah that's what I like about ASUS ^_^.