Vista being painfully slow was not limited to low-end machines. I had a fairly powerful (8GB+ RAM, new i5, etc.) gaming rig when it came out, and everything was slow on it: I'd click something in the interface and have to wait 5+ seconds for it to respond, Windows Explorer would crash randomly, etc. Even booting up seemed to take forever. Upgrading to Windows 7 fixed all such issues, and I still have the machine to this day, which I've kept with Windows 7 (although I upgraded the GPU).