I've been using Ubuntu Linux 90% of the time, and Windows XP 10% of the time, for about a year and half now. I've been keeping an eye out for Windows 7, though, as it seemed like a good Windows after the disappointing Vista.
So when I saw that Windows 7 RTM was already available at MSDN AA, I decided to give it a shot, having never seen it in action. I was expecting problems, since this PC is based on components made in 2004, so it is quite old. I was pleasantly surprised to see that it worked quite well, even before installing any drivers manually. Networking worked, sound worked, the spiffy Aero desktop compositioning worked. (My tv-tuner, Terratec Cinergy C PCI, didn't work, but that's no biggie — it works in Ubuntu.) Then I tried some OpenGL — oops, no hardware acceleration. No problem, I thought and went to install the latest drivers for my Geforce 7600 GS (AGP).
After the driver update I tried Tomatoes, worked just fine. Great! I went on installing Eclipse and setting up my workspace for the game project going on. And what did I find out: it was running very slowly, barely making 40-50 fps and fluctuating a lot! What the hell, it works solid 60 fps even in Linux (it's capped to 60 fps, so in reality it would run even faster), not mention Windows XP!
Then I thought, ah, the Aero effects, obviously they would affect the performance on machine this old. Disabled Aero, tried again: same results. I tried plenty of older drivers, plus a new set of drivers released a couple of days ago. Nothing changed. It would sometimes reach 60 fps when there was not much to render, but especially the water shader was killing the performance. This was not acceptable, I mean it does not really motivate me to develop something running too slowly, when I know it works much better on this very piece of hardware I've got.. Of course I understand that it will run slower than in XP (on this old PC), since W7 requires more resources to run, but it should not make this big a difference in fps.
After asking about the problem on Windows 7 forums and getting nothing, I decided to admit my defeat.. I guess either the OpenGL drivers just are not what they were before, or this PC is plainly too old for W7. I suspect the first. Of course, OpenGL has always been the ugly step child in Windows world while Direct 3D is receiving the love, so.. Too bad, really, I was starting to like W7.
I went and dropped back XP, and boom, everything runs fast again. Ubuntu dual-boot comes a bit later.
However, I might try W7 on the laptop of mine, that is currently running Vista. Vista seems too bulky for that cheap laptop, starting up very slowly etc., so I suspect W7 might help a bit. Indeed, I will probably see how the install goes on the laptop. Stay tuned for my report!
UPDATE: Writing this from the laptop running W7. Seems to be working fine, except the smart card reader. Better than Vista, that's for sure.