System Usage from Most to Least Important: Playing WoW, video editing, photo editing, watching movies, writing essays, web browsing
Parts Not Required: Keyboard, mouse, headset, speakers
Preferred Website(s) for Parts: Newegg.ca
Country of Origin: No preference
Parts Preferences: Motherboard and Monitor: ASUS, Case: Cooler Master, no preference for the rest
SLI or Crossfire: Yes
Monitor Resolution: 1920x1080
Additional Comments: I'm trying to decide between a Mac Pro, a MAINGEAR SHIFT, or a custom build... The Mac Pro seems like it's over priced, but I'm getting sick of running Windows. It needs to be able to run WoW on Ultra settings with no lag, and be able to handle addons for the game so that it doesn't nerf my frame rate.
Your WOW will lag because of your Internet connection, not your computer (if you spend $600 or more on the build). If you want to spend $6,500, you should start with awesome monitors. Like three 30" 1080p screens or three 28" 1900x1200 screens. That's $750 to $1000 right there.
Then you'll need a home server to back all your data up to running RAID 10 with 4x 2TB drives (That's 4TB of storage). Counting the wireless router, that's $800.
Are you interested in 3D? Because maybe we should be looking at a single nice 3D screen and two similarly sized ones to go next to it.
Considering your outrageous budget, there's absolutely no reason to settle on graphics. It's a fact that GeForces do better in WOW (not that it'll matter with the hardware you could afford for $1500), so you should get two GTX 580 3GB's. Then you won't be limited by your frame buffer and the GTX 580's can own anything at 3600x1800 or smaller.
And of course you'll also need a ridiculous gaming laptop with a wireless go anywhere blue laser mouse--so that you can max out WOW when you're on the go or eating lunch on the couch.
I know you're sick of Windows, but I'm not so I don't have Mac Alternative. I was going to put together a server and gaming computer build, but I got lazy. I'll come back tomorrow.
I agree with Soma42 though--you could build 6 great computers for $6500.