Thanks for the replies guys, and here is a little update.
I have upgraded my psu to 650w as recommended. it was not cheap upgrade!
So, the burning question NOW is which OS!!
I am forced to chose between a 32 bit Vista-XP business which allows to switch between the two as you please. So one can be instaled, then upgraded to Vista, or XP insalled and upgraded to Vista if needed. Now this is pricey, 200 dollars.
Another choice is simpler and cheper - a 64 bit Vista Home Ultimate.
Third choice is similar in that but different OS - XP P 32bit.
SO... is going 32 bit a good idea or better go with longer outlook and take 64 bit? Is Vista Home a decent OS in 64 bit what will run SH4 without issues? My specs are good, so I hope it will be plenty ... adn the GPU is good too so it wont suck the memory so much.
Help me out with OS advise, i Have to order soon!!! I have may be a day or two left before the machine is ready.