You should also consider to buy a previous generation HD 6850, although its more power hungry than the one you selected, you'll get a bit more processing power.
Also, maybe a less powerful CPU to add a SSD for your OS, you will notice the difference in load times and snappiness. (Intel G620 and an Agility 3 60Gb for example) Be sure to select a motherboard with sata III ports to enjoy full speed of you SSD.
All if you can stick these components into your budget of couse
Home: i5 3570K, A50 (Enermax Fan), P67A-GD65, Corsair 8Gb, MSI GTX560Ti OC, 2x Force 3 F90 RAID-0, Spinpoint F3 1Tb, One Hundred, Earthwatts 500W, ASUS MX239H, Win 8 Pro
Work: i5 760, P7P55D, 8Gb, Quadro 4000, WD20EARS 2Tb, VG236, 3D Vision, Win 7 Pro