Part 1: Patch uxtheme.dll And Apply Custom MSStyles
Part 2: Modify bootloader configuration and OS descriptions
SetteMaxer is a freeware utilty that can easily tweak windows 7. It can be used to optimize windows 7 without the need of manually modifying registry keys. The interface is extremely simple, You just have to check the boxes and hit apply.
Although there are not many options and the tweaks are also familiar to the customization crowd, but it is still one of the first application for tweaking windows 7. Give it a try. It is only for Windows 7 beta systems.
Download: SetteMaxer for windows 7