4850 vs 8800gt vs 9600gt 1440x900 lanbox pc?

Hey guys, I'm in the process of building a small lanbox and was wondering what is the best vga for 1440 x 900 with best temps. I guess 4850 is out of the picture since it gets so hot so that leaves both G90's.

They all work at that resolution.

4850 is the fastest. I don't see how it's out of the question just because it runs warmer than others.

I have a $700 budget for the rig. I'm getting either a used fragbox or a thermaltake lanbox with a q6600. These little cases don't have the superior cooling that it's atx brother has...thats why I said 4850 might be out of the question...MIGHT.

You can also mod these cases (IE cut a hole in either side for fans)(preferrably near the front). I'd go with the 8800GT, or the 4850 (if modded).

I still don't have the q6600, is a dual core really better than a quad? Main pc usage will be gaming ^^ If so what will be the best dual core combined with my ddr2 667 ram?

Parts that I have
3gb ddr2 667
600watt ultraxfinity psu
19" Wide 1440 x 900 monitor
Keyboard n mouse, headseat n mic and some nice speakers

...e8400 is pretty good but if I plan to overclock I'll need to change my ram...and I'd rather stick with what I have 2x1gb pny and 2x512mb kingston both are blue pbc...I really don't know how overclocking with intel works as I was with a amdx2 5000+ be where I just needed to up the multiplier to 15 to get the magical 3ghz...but what I've seen with intel is that the fsb is the same speed as the mem when 1:1 so I can get 334x9 and reach the 3ghz.