Three different places, three flavors of Windows 7. All web development.
Computer one was a Core i5 with 4 gigs ram, windows 7 professional. All work development was actually done in a virtual machine running VS2005 which was transfered over to the machine and added under XP mode. With the full screen display and ability to drag and drop across desktops it was actually very difficult to tell when you went from one OS to the other. No issues here.
Computer two was a 64bit version dual core machine with 7 professional. Ran on the bare metal with VS2008. Only issue I had in the beginning was running asp.net web applications off of IIS7 when the application was not in the WWWroot folder. This really just needs a little configuration on permissions. Everything else worked like a charm.
Last computer, 64bit AMD chip with 3gigs ram, 7 Enterprise. Again VS2008 and again just the issue with IIS7.
The second two computers all had a version of source control (SVN or SourceSafe), SQL Express and other utilities. (Downloaded most item with the Microsoft Web Platform Installer).
64bit/multi-core cpu's and lots of ram make a huge difference in feel. I down grade the UAC security of 7 so that it doesn't bug me about everything and the user has to be the admin of the machine (really no different from other OS's).
Good luck and hope this helps you some.