i7 is pretty much the beast out right now. Although, I see AMD is putting out 6core processors. The reality is, as far as computing goes, audio isn't *that* much of a resource hog. Not like video production. As for the ram, you might as well just go for 8 gigs. Most good motherboard have 4 ram slots- so just get (4) 2gig sticks.
I looked a few weeks ago and the biggest SSD was 32gigs and it was a couple hundred bucks. Lots of people do separate drives for the OS and audio for speed. I'm no pro, but I really doubt that this is as much of an issue now, where even modest machines can do so much (someone more in-the-know, feel free to agree or disagree). No matter what, if your data is even kind of important, you'd be a fool not to back it up
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I think the biggest reason people have problems with windows machines is because they get virus, malware and junk from the internet. Lots of people don't connect their recording machine to the net at all. If you're computer savvy enough to get your computer disease-free I wouldn't sweat it. Again, this is where a good backup can come in handy (my machines back up nightly). Wireless or wired isn't really an issue.
I'll stress again, that just because a device has 64bit drivers available it doesn't mean they work well (yet). Do a google search and see if there are any recent gripes about your hardware.
This is a detail, but one other thing to consider- get a decent dual head video card. Two reasons... 1) onboard video uses system resources that could be used for your intended applications and 2) dual monitors are sweet. Even if you don't get 2 monitors now, you may in the future.
My current recording computer is a budget single core AMD with a gig of ram that I built 6 years ago for about $500- its not aging gracefully and I'm maxing out at about 28 tracks with effects. I just built a new machine (not for recording) that has a quad core AMD Phenom with 4 gigs of ram and 3 hard drives (1 OS, 1 data and 1 backup). That cost me about $600. Sure, I could have gone with nicer and better, but even so, I would be VERY comfortable using that for my recording computer.