Its not actually for me, my nephew is currently using a be2300, with a 9500gt card which surprisingly runs his games(call or duty ,unreal,halo,etc) quite well, he now wants a quad to get a little kick, in his system, his board is a cheap msi board with no overclocking features(although a good board never the less) and it's am2, bios upgraded to am2+, so i was thingking of picking up a a phenom 9550 or phenom 9650, to put in. I know those arent powerhouses, but would they give his system so balls?
If he uses his computer for gaming...
then you should upgrade the video card!
the 9500gt is a very poor card.
I dont know your budget... but a couple of good cards for the price
are the GTX260 or 9800gt or HD4870...
but i need to know your budget
The 9500GT is weak. An HD4670 will be a nice boost, but won't require additional power.
No overclocking features make me ask, is this a pre-built PC? If so, the included PSU is probably the minimum needed for the job, and won't be able to handle a major GPU upgrade. You can pick up an Antec Earthwatts for it for $50-$60, which would allow you to put a 4830 or 4850 (or 9800GT) in it.
Be careful what CPU you get, make sure the mobo can support whatever wattage it needs. If it is only 65W, you could still put in a 5400+ for $70; that would be a big jump over the little BE.