You're not going to make many friends here if you're about to dump nearly $1000 on a system yet you can't set aside even $70 for a good power supply. If you're pressed for cash, either of these will power your system fine:
Very good, can power your 8800 really well and an overclocked Core 2 Duo. A lot of people slam Rosewill power supplies, but don't listen to them because a majority of them don't research before they post. JonnyGURU, probably the best tech reviewer for power supplies, gave this Rosewill power supply an 8/10. (The same rating he gave the OCZ GameXStream)
Another really good PSU. I had this with my 7900GS/Pentium D build, never had a problem. It can also power an over-clocked Core 2 Duo and 8800 card, easily.
EDIT: And don't come in here, and ask for advice, and when someone tells you to get a good PSU, say things like "Well I'm not skimping the CPU". You're putting every component in your system at risk, throwing some piece of trash PSU in a system with a $300 video card and a $230 processor. The way anyone will put it, is like this- You spent $220 on your E6600... Tell me, is it worth $50 to you? Because how much you spend on a PSU, is how much you're telling us you think your system is worth. Think about it. The power supply is powering ALL your components. Your optical drives, your processor, your motherboard, your memory, your video-card.
As for ram, get these dude-
$80.99- Free Shipping and very good quality brand. G.Skill right now, in my opinion, is a better ram company than Corsair or Geil.
For the video-card, honestly a 320 is fine. If getting the 640 means you can't get a good power supply or you can't get the different ram, then go with the 320. If you can get a power supply we recommended, get good ram and a good everything else, and STILL afford the 640, then get the 640, it'll be worth it.
you, my good man are on the same page as me.
ok, so, which one of the 2 PSU's would be best...
either is fine.
and the RAM..