TechRadar takes a look at twelve common Windows 7 problems and gives advice on how to solve them, you can check it out over here.
3. Aero isn't running
If Windows 7 isn't looking its best - transparency has been turned off, say - then the Aero theme may not have been fully enabled on your system. Click Start, type Aero, choose the "Find and fix problems with transparency and other visual effects" link, and click Next to launch the Aero troubleshooting wizard. It'll try to identify and resolve and problems. And if it doesn't, then install the latest driver for your graphics hardware. That could be all your system needs.
Some Aero features may be disabled in the Registry, though. For example, if Aero Peek (the ability to make open windows transparent to display your desktop underneath) doesn't work for you, then launch REGEDIT, browse to HKEY_CURRENT_USERSoftwareMicrosoftWindowsDWM and make sure EnableAeroPeek is set to 1, rather than 0.