Fast application switching is a problem on Windows now and will continue to be in the future. The issue is that the Alt-Tab method of switching between open windows is only useful if you have a small number of open windows. When you have dozens, it's fairly useless. When this switching method was first introduced, there simply wasn't enough horsepower to have dozens of windows open anyway, so it didn't matter. Times have changed, however. Apple's method of using Cmd-Tab to switch between applications, and Cmd-~ to switch between windows in that application is a much better design.
All the Vista-compatible applications I've tried have successfully started and run under Windows 7 beta, including several that were problematic under Vista, such as the ShoreTel client. There are the normal UAC annoyances, but they can be disabled just like Vista, if you like to live on the edge. As with all my Windows installations, I paid the performance penalty and installed a virus scanner and Windows Defender to keep an eye on viruses and malware.
This being a tablet, I was able to test those features too. It's much the same as with Vista, no problems there. Of course, with my newfound use of the left-hand taskbar, I had to move the Tablet Input Panel to the right-hand side of the screen. It might be a little faster than Vista, but I haven't noticed any significant performance increase on this laptop, and I'm not going to run benchmarks on beta code.
So Windows 7 is very nice and all, and it may be that it's is the best iteration of Windows yet, but there really isn't that much there, other than the improved taskbar. When Apple released Leopard, there were significant feature additions and improvements, like Spaces, Time Machine, and so forth. That type of step forward seems to be missing from Windows 7. In addition, there's still no compelling reason for businesses to switch from Windows XP, and that's Microsoft's biggest problem of all.
For the majority of business uses, Windows XP and Office 97 or 2000 are more than enough to handle day-to-day business tasks. In this economy, upgrading functional server and desktop operating systems isn't in the budget, especially when there's no business reason to do so. This isn't a secret, since the corporate response to Vista was lukewarm at best, and those that jumped on the Vista bandwagon initially certainly aren't going to be thrilled to make another leap to Windows 7 so soon. I do know that I'm in absolutely no hurry to move away from Windows XP as the corporate desktop except in some extreme cases -- it's just not worth it.
This leaves Microsoft selling to home users and power users, and relying on the OEM installations to push copies of Windows. The problem there is that by working on Windows 7 so soon after Vista's launch, Microsoft has effectively orphaned Vista -- why buy a copy now when Windows 7 is right around the corner?
In short, did Microsoft peak with Windows XP?