A cheap GPU like 9600 will barely play games at low settings at that resolution. Might be a painful time until you can replace the GPU.
For better balance a machine with a faster/upgradeable dual core like an AM3 motherboard and Athlon IIx2 240 and get a strong GPU, then upgrade the CPU to a good Phenom IIx4 in 6 months might be a mroe pleasant option. There are very few games that really make use of more than one core anyway (like Crysis and GTA4)
If gaming is your priority, then put max $$$ into the video card.
An AMD X3 720 or a propus 620 will work just fine for very little money.
Go cheap on the cpu and moderate on the motherboard.
An AMD 5xxx card will give you the best results. Buy the best on you can afford.
At a resolution of 1680 x 1050, you don't want to ignore the CPU. An AMD X3 720 will bottleneck the performance of a 5850. A Phenom II X4 955 would be the balance point (or maybe just a smaller bottleneck. How does the Phenom II X4 955 compare to the Intel Core 2 Quad 9550?) for a card that powerful. But both of those won't fit in your budget at the same time.
Good points. Considering the 620 Propus is half the price of the i5, I may be able to go with a 5850. What are some good motherboards for AM3? I haven't been keeping up with chipsets for AMD motherboards.
Sorry I missed that. So, would you recommend the 620 or the 720? The 720 has one less core, but is clocked higher. Then again, you can get a dual core in the 3+ GHz range for even cheaper (which is indeed what I did in my first post).