Just to circle back around, I'll be hitting MicroCenter this coming weekend for the final parts of my build. I've decided to go with the 3570k, not sure which board yet but I figure I'll decide once I'm there (which will likely take a while, and my wife will love me for it).
I looked into what vt-d is, and decided it's really not necessary at all for what I'm doing (and probably not necessary in any desktop chip). VMware Workstation doesn't even support it, and that's what I'll be working with.
16GB of RAM for now. I went for the Samsungs, which were only 4GB modules, but there was a deal on them, they're well reviewed, and low profile is nice. I've done all the math in my head of what my limits will be, and I don't think I'll ever be pushing it with 16.
I considered AMD chips old and new for a while, but decided I'd feel like I wasn't getting a real upgrade. It didn't look like they were going to out-perform my Core2Duo by much on single-threaded tasks, and while several cores would be nice, the 3570K will probably still come out ahead anyways, for my needs. I do still game too, so the benefits are clear there.
An i7, while nice, just didn't seem worth the extra cash. I can't really see a clear value for virtualization. If anything, it seems like things can get a little wonky depending on how your VMs get assigned to threads. At best, you'll see a performance bump that... probably isn't significant enough to see. The rule I've always gone by is that to notice a difference, you need at least a 20% increase in speed, and I don't think HT is going to do it. I'll save the money now, and spring for a decent sized SSD once prices settle down here. I've been tempted, but prices still seem to be dropping so I'm going to see where they go.
SBE was also a consideration, but to get any real benefit I'd have to go with one of the 6-cores, which are very firmly out of my price range (the bang for the buck starts getting pretty out of whack at that point, too).
I considered some slightly older Intel stuff too, but what it really came down to is that this is replacing a 4 year old build, and this once will likely need to last another 4 years. Aside from the obvious performance benefits, I'll feel like my money is best spent getting the 3570k, which really is a great value.
Thanks for all the suggestions, I look forward to getting this thing built!