Save some $ here:
$93 shipped - $20 MIR = $73!!!Corsair TX 650W ATX12V Power Supply - CMPSU-650TX
I'd also stick with your p45 mobo, I don't think the 1 x8 PCI-e slot is going to limit you. Yes it would be nice to have 2 16x PCI-e slots, but for $50 more is it worth it???
Now I'm also going to assume that your going to be using a 64bit OS, since you selected 4 gb's of DDR2??? If not than you won't be utilizing all 4 gb's of DDR2 with a 32bit OS.
The GPU that Emp linked is a good one, but you'll only be able to cash in on "1" rebate of $20, so keep that in mind.