I love my XP and can't get along with W7_64 on my i7-3930k (12 HT-Cores, 16g ram, ssd).
If I run XP64, which limitations does that mean? As far as i found there is only "no automatic SSD swiping", 16g ram works.
Are there any power saving modes or cpu speed modes that XP64 doesn't support or anything else?
XP64 was a "test" OS. Maybe on your rig you can solve all the "small" problems that appear but on a larger scale, ive never seen it well deployed. It would always have various problems with most applications and would have strange behavior. Like said before, just go for W7 or V64 and remove Aero.
Or you can install Server 2008 R2. Everything works perfectly, never look back. I currently game on it, have a small "lab" assembled, Teaming, Raid, CF everything works like a charm. Boot times can increase a bit, depending on the server roles installed, but hey, its does a lot more than just a W7 Pro/Business/Ultimate Version. Has a really small memory footprint too. W7 Drivers work with no problems.