ZDNet have an article comparing the performance between Windows 7 (build 6956) and Windows Vista RTM/SP1. This is a really good read as it highlights the performance boosts that W7 is already starting to show:
http://blogs.zdnet.com/hardware/?p=3182&page=1
http://blogs.zdnet.com/hardware/?p=3182&page=1
What we have here is one set of data points for one particular system, but I think that the results are very promising. The fact that Windows 7 comes out top in three out of four of these tests at this early stage is very promising indeed. The boot time and PCMark Vantage results are particularly good.
I remember benchmarking an early pre-beta of Vista and it was awful compared to XP at the time. At this stage I can only assume that the RTM release of Windows 7 will offer more performance than this build, and will at the RTM stage be better than Vista. This is great for those who are concerned about the OS soaking up too much system resources.