Just bought new PC just for D3. This setup should run it just fine(I hope):
Motherboard:Asus P8P7 (The most bought motherboard when using either i5 or i7)
GPU:Nvidia GTX560 1,5gbit
CPU:Intel i5 2500k
HDD: WD Blue 1tb (Going to order 250gb SSD hdd as soon as my paycheck clears out )
Monitor: Acer H233H 23" widescreen
Keyboard: Logitech G19 (I know, I paid 190 euros for ~2" LCD monitor on my keyboard, its crap I tell you )
Mouse: Good old MX518! Dats the best, served me for 8 years now and still rocks in every single game, FPS or RPG whatever
By the time it comes out the GPU will be a 570, I'll have 8-16GB of RAM, and possibly a SSD. I'm really pushing it with that CPU when I make the GPU upgrade, but I'm expecting it to not bottleneck. CPU will be in the next wave of upgrades in a year or so...possibly a new mobo as well.
Mobo: Gigabyte G1.Sniper
CPU: Intel Core i7 960
RAM: 6 GB
GFX: Gigabyte GeForce GTX 470 1280MB (super-overclocked edition)
Storage: 1TB 7200RPM, 2TB External Drive (main drive used to be 128GB SSD but it died after less than a year)
Monitor: 26" Old-As-Dirt 720p TV (my weakest link)
My setup is in my signature. I'm going to update my computer very soon though with an i7. I just missed the boat when I bought this beast so a new motherboard, ram and processor will be coming. Ebay is the best place to find graphics cards too.