It's up to you with the PSU. It's really just to give you an idea of the type of PSU to buy. You don't have to go with their recommendation, mine was about 500w but I purchased a 700w just incase I wish to upgrade at a later date.
The one I bought was Arctic Power 700W PSU - With PCI-E, 4x SATA, 20+4, ATX12V, 8pin +12V Connectors - Retail Boxed -
http://www.ebuyer.com/product/124927 Costs about the same price in EU as the one you posted (or so my currency conversion told me) they both roughly about ﾃつ｣41 which in EU is about 52 EU.
Anyway my specs:
Motherboard: nForce 590 SLI: Foxconn C51XEM2AA - ﾃつ｣40/50 (60/70 eu)
Processor: AMD Athlon™ 64 X2 Dual Core Processor 6400+, MMX, 3DNow (2 CPUs), ~3.2GHz - ﾃつ｣90 (100 eu) - Intel are better but i've always been an AMD supporter.
Memory: OCZ EPP 4Gb (2X2048Mb) PC2-6400 DDR2 Dual Chan SLI Cert ﾃつ｣70/80 (80/90 eu)
Hard Drive: 2x Maxtor 500GB Hard Drive SATAII ﾃつ｣50 (60 eu)
Video Card: 2x BFGTech GeForce 8800 GTS OC 512MB ﾃつ｣150 each (160 eu)
Power Supply: Arctic Power 700W PSU ﾃつ｣41 (52 eu)
Case: Antec Nine Hundred ﾃつ｣60 (70 eu)
Total cost of about 600 eu. Could be cheaper now though with the massive price drops. As for playing games, take away one of the graphics cards and I can run any game max settings. The game which I play most is Call of Duty 4 and I usually sit around 160 FPS and can have it running up to 250 FPS.
*EDIT*
I was looking at some comparisions on a website and I couldn't find the exact card you're going after however there was a similar card "PowerColor Radeon HD 3850 Xtreme PCS 512MB" just branded by a different company and it gives bench marks for different games and it shows for example in the Call of Duty 4, the FPS for max settings with that card was 62.2. Above that was:
Nvidia GeForce 8800 GT 512MB - 79.9 FPS
Nvidia GeForce 8800 GS 384MB - 66.2 FPS
ATI Radeon HD 3870 512MB - 62.2 FPS
Don't know how much the card you're buying costs but I do know the 8800 GT OC costs about ﾃつ｣100 (110 eu) and for an extra 10eu the OC2 model can be purchased. and the site I am on shows that "Asus GeForce 8800 GS 384MB GDDR3 HDTV/Dual DVI (PCI-Express) - Retail" costs about ﾃつ｣59.99 (60/70 eu). You got the links to any of this hardware you posted?
