system rehaul on a budget - how does this look?

I am replacing my power supply, motherboard, RAM, processor, and video card (and DVD drive if i can, because I want to keep my PATA hard drive and my current DVD burner is also PATA - most motherboards now only have one PATA connector)

I'm on a semi-tight budget right now, so I'm going for expandability. Later this year I'd love to jump to a Q9450 (I do a lot of video editing and 3d rendering in addition to gaming) and a 9800GT or even GTX.

Intel E2160 processor $70
Gigabyte GA-P35-DS3L motherboard $90
G.Skill 2GB (2 x 1GB) PC6400 memory $45
Sapphire Radeon 3650 GDDR2 version $80
OCZ GameXStream 700W power supply $135

My budget is about 450 dollars after tax and shipping.

I have some specific questions:
Should I spend the extra $20 on the video card and get the GDDR3 version? Right now the most taxing game I own is probably Half Life 2 Episode 2. I plan to get a new video card before this fall.

Should I get the single 2GB stick of RAM for the same price?

Should I save $30 on the PSU and get the 600W version instead? (Or even a completely different model?) I may go SLI after my 9800GT or whatever becomes insufficient down the road, although at that point Nehalem will probably be out and I might be looking at a total system rebuild again anyway. (Or is it a sure thing that PCI-Express will still be the standard graphics slot even after Nehalem?)
Obviously 700W is total overkill for a 2160 and a 3650, but what about a q9450 and a 9800GT (or two?) Should I be instead looking in the 500-600W range?

Any other thoughts? Thanks for your time.

would the 700W be enough to power dual 9800GTXs (assuming they have the same power requirements as the 8800's?)

If I were planning on just getting a 9800GTX (or 4870?), how would my PSU requirement change? I could probably do with the 600W model, couldn't I?

That is true.

I want to be able to run a q9450 and an 8800/9800gtx. Are there any power supplies that stand out on price vs quality that could run that? Does Mushkin make good power supplies? How about this one? http://www.newegg.com/Product/Prod [...] 6817812004
Four 20amp 12V rails, plus it's modular and only 100 bucks. Is this too good to be true?

I think the OCZ would handle a 9800 card just fine.

As for other power supplies, I am partial to Corsair and Seasonic brands as those are the only two I have ever owned and have never been dissapointed.