The GTXs are overpriced and way out of your price range. I'd get either the 8800GTS or GT 512MB. If you don't mind OCing, you could get the mid priced GT and OC it up to the top (and save $30). That GTS does look tempting, though.
What resolution do you play at? I'm not sure how GPU demanding AgeOC is though. If you must stick to evga, that 8800GT is the best value there. For lower resolutions (1280x1024) the evga 8800GS superclock for $110 AR is an excellent value. 16x10 or above res, move up to the 8800GT.
If you switch brands, there is an 8800GTS 512MB for $170AR on th egg. Also, 9600GT's for $120 AR.
I am in the AoC Beta atm, my system specs on my "Loaner" PC, take into effect i know nothing of this rig lol, a socket 939 AMD OC'd to run at 2200, 2 gigs of Corsair XMS DDR, and 2 7900's in sli running on an ASUS mobo. I typically get around 30-50ish Frames on this set up. Forgive the lack of info on this system i am just using it till all of my stuff gets in this week, will repost specs tomorrow night.
I have the eVGA 8800GT base version and despite the specs saying 600Mhz core, its standard is 650Mhz and is easily OC'able to 700Mhz. I have the original 8800GT though so the cooler sucked and was loud so I replaced it with a Zalman VF-900, thing is cool and quiet now.
$/fps is best for the 8800GT. But I'm not sure how well it will handle 1900x1200. Does just fine for me on my 22" monitor though.
Articles summed up
-Heat: GT is 15% hotter. I prefer the new dual slot GTS. I do have a ZALMAN VF900 on my 7900GTX that I might be able to transfer to the new card.
-Noise: Both cards are similar.
-Performance: "Overall, the GeForce 8800 GTS 512 MB is interesting for a few reasons. Based on a largely more powerful G92 (24%) than the one on the GeForce 8800 GT, it manages to outperform the GeForce 8800 GTX." I think the average difference in performance is more like 10% between the GTS and GT.
Due to my 24", I would rather have the extra throughput and memory bandwidth that the GTS has to offer. The GTS also has a much better cooling option than the GT which I could only find with the small diameter fan. Though possibly my VF900 would be the better cooling option on the GTS? My Antec P180 case has great airflow.
My plan is to wait a week and look for a lesser rebate option and hopefully end up with a GTS for $190 or less.