Upgrading video card on old PC

Hey all, I am looking to upgrade the video card on my lil brother’s old computer so he can play some of the newer games. I’m looking to get a 9500/9600GT since theyre quite cheap, and I dont need the top of the line card. Plus my mobo/PSU prolly wont support it. The mobo is a Asus P5GD1 PRO: http://www.asus.com/products.aspx?modelmenu=1&model=632&l1=3&l2=11&l3=24 and the PSU is this crappy one: http://www.ciao.co.uk/ASUS_Atlas_A_36F_Power_supply__6502800
Will they be able to run a 9500/9600GT? My main concern is the PSU. I hardly know anything about building and stuff like this. But I heard the 12V rail on the PSU is quite important. The reading of the +12V (under voltage) is 18A and the reading of the -12V (under current) is 0.8A.
Cheers
Answer #1
well with a pc like that i wouldnt suggest the 9 series. The single cores bottleneck as well and if you need a psu get a name branded one not generic. Try get an Antec, Thermaltake or Corsair one or similar
Answer #2
If the 12 volt railing is 18A then you have more than enough. I suggest you get the 9600GT because it will be “100x” better than the 9500GT.