as per http://answers.microsoft.com/en-us/windows/forum/windows_7-files/change-location-of-temp-files-folde...
To change the location of the System Temp folder, follow the steps given below.
1. Right click on Computer and click on Properties. In the resulting window with the basic information about your computer
2. Click on Advanced system settings on the left panel resulting in a dialog box click on the Advanced tab a
3. Click on the button near the bottom labeled Environment Variables.
4. You may see both TMP and TEMP listed in the section labeled User variables for (account). That's the common location; each different login account is assigned its own temporary location.
5. In the Variable value Edit box you may specify the path to the directory that Windows and many other programs will use for temporary files.
Be sure and repeat that process for both TMP and TEMP.
You'll need to restart any running programs for the new value to take effect. In fact, you'll need to restart Windows for it to begin using the new value for its own temporary files.
