Yes i have installed Windows 7 Beta Build 7000 and at present i m Downloading Windows 7 RC.
It looks really nice to work on Windows 7 system with whole new looks and Features. The Window users who have been using XP or Vista will definitely like this one as it looks to be a quite different from them(XP or Vista). One thing which Windows 7 Developers has tried to implement in Windows 7 is to short out all the problems which the users have been facing in Windows Vista and to Add up many more extra features like Action Center, Multi-Touch features and many more.
In Windows 7 one can have a nice Glassy look Desktop with the Icon Docked Superbar(called Toolbar in earlier versions of Windows). The date and Time displayed at the right corner is also nicely presented.
Note: It is Officially not recommended to Upgrade from Windows XP to Windows 7. It is advised to do a complete fresh installation. Upgrades are Officially advisable for Vista SP1 users only.
Here are some useful links for Windows 7 Installation.
Minimum System Requirements for Windows 7 Installations
Link
How to Upgrade from Windows XP to Windows 7
Link
Windows 7 Action Center and its uses
Link
Multi-Touch feature of Windows 7
Link