I don't think it will perform as well as the one you've chosen, but your better off not spending too much on a DX9 graphics card and wait until the dx10 graphics cards come down in price.
Everything except the ViewSonic (Got that yesterday) and the Sound Blaster (Got that free from an '02 machine) cost about £650 but I got XP Pro from a friend with a Corporate licence. Everything but the RAM is from Novatech and the RAM is from OverClockers.
Oh and I have a cheap JeanTech case, but that cost like £20. Still a great case though.