Go with a Geforce 7600gt graphics card. It only costs about 20 bucks more and its a 256 card, not a 128. You can buy them already OC'ed from some manf. This card should also last you until you can get a Windows Vistas Compatable card once the prices drop.
You also might want to think about a E6400 ($224.00) instead of the E6300 (184.00). While both are great, the 6400 is a dream to OC. I mildly OC'ed mine from 2.1 (stock) to 2.4 (Base on a E6600 which is a couple $100 bucks more) and it actually runs cooler, and with the right memory it can go to 3.0 w/ stock cooling I have heard.
I know w/ these 2 it ups your budget $60.00, but I think your end result would be much better.
EDIT: You could make up this cost difference a little by getting a cheaper case. This is the one I bought
http://www.newegg.com/Product/Product.asp?Item=N82E16811144026
Its almost $4o bucks cheaper than the one you picked out, and personally if I built another PC it would be with this case. It looks awesome in person, It has great airflow, even with the processer OC'ed it idles @ 42 celcius and rarely gets over 50 when loaded.
Make sure you get the right memory and not the 533 mhz. You can only up the frequency to 600 and keep it stable, and thats w/ good value Ram. Because with the wrong Ram your processor OC won't work.
My PC using this box is a E6400 OC'ed 2.4, ASUS P5N32 SE SLI Deluxe mobo2 GB Ram, Creative X-fi sound card, 7600GT OC'ed, 250 Hard Drive.