Those are very wrong parts to have picked out man. First things first, you don't need anywhere near 1kw to power that system. That is a total waste of money when $150 could have gone to the mobo + CPU instead (which is lacking, but I'll talk about that in a minute). Realistically, your system needs 450W
tops. I know an e7300 with a 4830 uses 300W at load. Your system doesnt take that much more. I'm even guessing 350W - 400W at very most.
You need to keep in mind that you should always get a PSU that fits your system requirements. PSUs usually peak in their efficiency at around 40%-70% of their max load. Getting that PSU will mean that you are realistically running your PSU at a very low efficiency since only when you have everything fully powered up do you start to hit the higher efficiencies. Most of the time your computer will be idling at 20% or 30% of your PSU load, and the efficiencies at that range can really start to get pretty crappy.
To make matters worse, that PSU you chose is not that great to start with. You could find cheaper PSUs from better brands that actually perform much better (in terms of efficiency and regularity of its voltage supply to your components).
For a more detailed explanation of what I was trying to explain, check this out.
AnandTech: Debunking Power Supply Myths
This is a much better choice. It also has a whopping 41amps on one single rail, which I personally prefer. It also lets you spend $150 on a better CPU and mobo.
Newegg.com - CORSAIR CMPSU-550VX 550W ATX12V V2.2 SLI Ready CrossFire Ready 80 PLUS Certified Active PFC Power Supply - Power Supplies
Next is your CPU and motherboard. By no means is the 6400+ X2 a slouch, but its really by no means a fast CPU anymore by today's standards. Your graphics card is also rippin fast, which might be limited in games by your limited CPU power.
I suggest this.
Newegg.com - Intel Core 2 Duo E8400 Wolfdale 3.0GHz 6MB L2 Cache LGA 775 65W Dual-Core Processor - Processors - Desktops
And this motherboard to accompany
Newegg.com - GIGABYTE GA-EP45-UD3R LGA 775 Intel P45 ATX Intel Motherboard - Intel Motherboards
You could also consider going for a quad core CPU. This Q6600 a little slower (maybe 6 or 7fps slower in CPU intensive games) but will pay off in the year ahead when more applications start to make use of the extra cores in the thing.
Newegg.com - Intel Core 2 Quad Q6600 Kentsfield 2.4GHz 2 x 4MB L2 Cache LGA 775 Quad-Core Processor - Processors - Desktops
Lastly, may I suggest this ram? I think it looks much better than that gold thing you chose
Newegg.com - Intel Core 2 Quad Q6600 Kentsfield 2.4GHz 2 x 4MB L2 Cache LGA 775 Quad-Core Processor - Processors - Desktops
Oh and may I suggest this ram? I think it looks much better than that gold thing you chose
Newegg.com - OCZ Reaper HPC Edition 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory - Desktop Memory
As for the hard drives you have, I suggest you use the 500gb one as your boot (and game) drive and the 250gb one to store whatever else like pictures and things. This is simply because the 500gb WD drive drive is faster.