Core i7 Build - PSU and comments

Hi all,

I'm after a bit of advice picking a new PSU, and some comments on my planned build.

I'm currently planning to put together the following:
Asus P6T Deluxe
Intel Core i7 920
6GB (3x 2GB) OCZ DDR3 (already bought)
3x Hard drives (2x 500gb, 1x750gb)
ATI 4850 (only got one atm, not sure whether I want a second)
2x DVDRW

I'm primarily building this for my work rather than gaming, so I don't need the best graphics - just something thats pretty good.

What size of PSU would I need? I went for an Antec last time (~500w), its done me fine, and I've used Enermax in the past ("basic" 350-400w one). I want a good-brand PSU but not a crazy high end which costs the earth, something around £50-70 would be ideal :) I believe I should also get one which is EPS so its got the right connectors?

Do you think with only one 4850, I'd be ok with something like the 650W Xigmatek NRP-MC65?

Finally, I'm planing on re-using the Antec p180 case I have (I don't think there should be any problems?) - so I need something cheap (£25-35) to put my old build into - any suggestions?

Any/all advice and comments would be much appreciated :)

For two (of thouse) gpu's I would have a Corsair HX620.

Also for the Hard disks i would get three WD640AAKS's

I'm building myself . The i7 920 excits me. Gonna have some fun! Me, I'd go for 700w so that you will have a little extra upgrade power. I'm going to use an old OCZ Gamestream 700 I used in a previous build...New Egg has em' for around $90.