To save a bit of money on the case i recommend the Jean Tech Phong II . Its not as pretty as some of the more well known cases but imo it looks nice and it has a great build quality for the price
It comes with a little tool kit with all the screws and rubber grommits things you'll ever need. There is a front 140mm fan and a 120mm back fan already installed with adjustable speed controls on the front - even on full they're very quiet. The intakes also have dust filters fitted, after 5 months of running in quite a dusty house mine still has no dust in it. Theres also a temperature meter on the front , although i don't know how much to trust the readings it gives.
Also as some have said got for the 8800gt instead of gtx , i think the 512mb will be enough unless you plan on running games at very high resolutions on a 24" + monitor.
And go for good a good make of ram (OCZ , corsair , kingston etc) but look for ones without the shiny heat sinks as it pushes up the price and unless you plan to over clock they won't be that useful.
As a vista user I'd recommend it , I've been using it for some months now and I honestly don't miss XP at all.