You may notice that your c:\windows\csc folder may be massive (10% of your drive max by default). CSC stands for client-side caching. Windows offline file browsing uses this for its network cache.
To disable this in XP: Open up Explorer go to Tools -> Folder options -> Offline Files tab and untick Enable Offline Files.
To disable in Vista: Go to the Control Panel, search for Offline Files and disable. Before disabling click view Offline Files and delete everything in there.
If that doesn’t work boot into safe mode access the csc folder and delete everything in there.
Microsoft’s answer to DLL Hell that was introduced with Windows XP: side-by-side assemblies (winsxs).
“The advantage of winsxs over system32 is that you can have more than one version of a particular DLL with the same name.”
In other words don’t touch this folder unless you really know what you are doing 
Source: http://davidlenihan.com/2007/07/winsxs.html
Add additional time zones:
1. Right click on the clock in the taskbar and select Adjust Date/Time.
2. Click on the Additional Clocks tab.
3. Check the box for either additional clock 1 or 2 and select the time zone.
4. Type in a display name for your click and hit OK.
Now when you hover your mouse over or click on the clock you will see the additional time zone.
Tip: You can also add additional clocks to the sidebar by adding more clock gadgets.
If you’ve ever wanted to slim down your Vista install disc or make it completely custom you may want to look into vlite. This comes from the makers of nlite which does the same thing for XP.
http://www.vlite.net/
View the SQL Server error log by using SQL Server Enterprise Manager or any text editor.
By default, the error log is located at Program Files\Microsoft SQL Server\Mssql\Log\Errorlog.
Rather than running applications in a virtual machine for testing purposes it possible to do so on your own machine but have the applications in a virtualized space. That way you can turn on application as you need them, instead of having their services on all the time.
This is how I run iTunes and test out smaller indie games. The personal version is free.
http://juice.altiris.com/node/86
http://www.altiris.com/Products/SoftwareVirtualizationSolution.aspx