Or just upgrade your video card and be done with it. ~$100 should radically change the graphical fidelity you experience
Seriously, a GTS 450 or a 6770 is going to rock your world.
A handful of the latest titles are going to give your e5400 a rough time.
I have a e5400 in a cruncher that I turned up to 3.25Ghz with one reboot, no sweat and no instability (BOINC and F@H for days/weeks) so you might be able to squeeze more blood from that stone.
That said, a 20" monitor even at 1600*900 is going to give you a lot more usable computing desktop area while keeping your GPU requirements a bit more modest and affordable.
Sharing if you are a cheap bastard:
http://www.tigerdirect.com/applicat...EdpNo=154506&csid=ITD&body=REBATES#RebateInfo