You can get a nice P45 based motherboard for <$100
The Q8400 2.66 is a better 45nm part for $169.99
4gb of good ram should cost $50. DDR3 is not worth an extra price premium.
An evga GTX260-216 is $149 after rebate.
Is ultra a psu that you want? You can get a corsair unit for your system for about the same price.
The AMD fanboys will chime in and be able to tell you how a phenom system will be even more competitive.