The easiest way to start Regedit is to hit the Window key on your keyboard, type regedit, and then hit Enter. (You can also do this by clicking on the Start button as well.)
Before you make any changes it's probably smart to back up the key or subkey you're planning on tinkering with. Once...
aero snap
background
buttonset
desktoplivepreview
dword values
extendeduihovertime
file explorer
ie8 title
login screen
minwidth
personalization
registry
registry backup
taskbar previews
taskbartweakstweaks
user interface
value data
windows 7
windows customization
Here are some of the changes that are being discussed as being a part of Windows 7:
New version of Windows Media Center
Gadget for Windows Media Center
Native support for multiple graphics cards from different vendors in one system
Gadgets integrated into Windows Explorer
Pin and unpin items...
calculator
gadgets
graphics support
installation
internet explorer
localization
media center
multitouch
network apis
performance
security center
start menu
system tray
taskbartweaks
user account control
virtual drive
windows 7
windows live
xml