If we want to oc a card we will need additional power but as GT 240 don't has any a pci-e power connector I think it's OC potential is less than a 9600GT - if you can grab a good GT240 ( with GDDR5 ) you might be able to reach 620-640 Mhz from 550 MHz.
I don't much about that mobo or it's bios options but I've heard that this mobo can be oced as well ( though not to a great extent ) - so it woulkd be better if he updates his bios with the latest version available.
BTW, here's my new rig score
CPU : AMD Athlon II X4 630 @ 3.5 GHZ with 1.41V
GPU :- 9600GT OCed to 767 MHz ( 765 ) / 1912 MHz ( 1900 ) / 929 MHz ( 925 )
Motherboard : Gigabyte MA785GM-US2H @ 4k
RAM :- 2 GB DDR2 @ 833 MHz ( 5-5-5-15 )
*img90.imageshack.us/img90/5747/20100819084052.png
*img843.imageshack.us/img843/3304/20100819081839.png
*img541.imageshack.us/img541/8264/20100819081853.png
*img695.imageshack.us/img695/493/20100819063805.png
3D Mark score - 13160
SM 2.0 score - 5457
HDR/SM 3.0 Score - 5149
CPU Score - 5055
BTW, check out my rigs pics
*www.thinkdigit.com/forum/hardware-...lite-430-discussion-thread-2.html#post1275153
For Detailed OC settings :
*www.thinkdigit.com/forum/discussions/121070-overclock-listing-thread-4.html#post1275158