You don't need a 1000watt PSU...for those components you listed, a 500-watt PSU would run them.
The GFX card seems like a bit much, a 7900GT or X1900 would run literally anything for less money. There is a 7900GT for sale on the forum for $200 with extra's, or you can get it alone for $199 after rebates on Newegg.
Motherboard is a little pricey, you don't need one that's $250. Try getting a cheaper one.
If you need high-performance RAM, than your pick is okay. But I've always used Value RAM and it has worked great.
Also don't skimp on the processor, get at least Core 2 Duo E6600.