Gonna start up a thread here detailing my experiences getting Windows 7, and more specifically, CoH, up and running.
Before we begin, here's the system I'm running:
* Asus P5Q Pro motherboard
* Intel Core 2 Duo E7200 (2.53GHz, OC to 3.16GHz)
* 4GB PC2-6400 RAM
* 2x 500GB SATA-II hard drives
* Gigabyte Radeon HD4850, 512MB GDDR3, Catalyst 9.7 drivers
* Windows 7 Professional x64
This system was originally running XP Pro x86 so I wasn't looking forward to having to reinstall all my programs and copy all my documents back (heck, I'm still not back to where I was at this time yesterday). However, first thing I did before the install was check Asus' website to see if they'd released 64-bit Win7 drivers for the chipset and various motherboard components. They had, so I got right on the install. Copied all my documents (only about 40 gigs worth, turns out the bulk of my old XP install was program files) to my second internal hard drive, then rebooted to install Win7.
The installation process was a bit slow (contrary to what I've been told) but the system runs very well for a new install. No hiccups during the install, and I began by installing all the necessary drivers. Didn't have to reboot once, which was a pleasant surprise. First snag I hit after the install though was a fairly simple one - I use a wireless connection because I'm not close enough to run wiring to the router, and Win7 didn't find drivers for my Edimax wireless card. I ended up downloading the drivers on my MacBook and then transferring them to the desktop via my external hard drive (I've lacked a USB flash drive for a while, and hadn't missed it until this point). Began re-downloading and re-installing applications as fast as my internet connection would allow and had most of my basic stuff up and running within two hours. No compatibility issues with programs I've used, though I cannot stand Skype 4 and Skype 3 doesn't run well under 64-bit Win7.
Of course, my biggest concern was CoH - how would it run? Since I didn't want to wait to download both the live and test versions, I did it a little differently - I copied the CoH and CoHtest directories to my second hard drive, and then exported their respective registry keys to those folders. When it was time to get CoH up and running, I copied the two folders to the Program Files folder and then re-imported the registry keys. Left Aero on while the game was running, and noticed that while the framerate wasn't as high as it was under XP (usually 50-60 FPS while standing at Talos WW's), it was still well above what I'd consider playable (40-45 FPS in the same location). No complaints here.
In regards to the user interface: I don't like the Start menu. Specifically, I hate how the "All Programs" menu doesn't pop out like it did under XP, because scrolling through dozens of programs in a tiny little area isn't conducive to good user experience - at least it arranges the programs alphabetically automatically, unlike XP which required you to do it manually. I prefer the Win7 Explorer window over that of XP but it still seems a bit clunky compared to the OS X Finder. Aero Peek is really nice (though Win+Space seems more like a superfluous addition than anything functional, since you can't do anything while the windows are hidden). Notably, I completely disabled UAC since I'm pretty sure I know what I'm doing on my own computer, and I also disabled the "resize windows when I drag them to the edge of the screen" feature since I often intentionally drag windows around and don't want to resize them in such a manner. I then discovered that Win+D will show the desktop, and pressing Win+D again will restore all windows (much like F11 does for Expose in OS X). New taskbar is very nice and the ability to rearrange items there on-the-fly is something I was quite happy about, since I had to rely on a third-party utility to do the same in XP.
I'll throw more experiences out there as I can. Overall I like Win7, mostly for the fact that it'll run on older hardware (I've never been one to believe that advancements in hardware should be used as an excuse for sloppy and lazy coding). It's no OS X, but it's leaps and bounds over XP and Vista.