By default Windows installs all the programs in C:\Program Files directory, you might want to change it if your C drive is running out of free space. Moreover, if you like to install any antivirus program like Kaspersky or Norton you need to use this tweak as they won’t give an option to change the default installation directory during product installation.
To start with this guide, make sure you have enough free space in your new directory which you are going to make as default one.You need to do a small registry change in order to change your default installation directory as follows:
1. Type “regedit” in Vista start menu search box or in Run dialog box (for XP) and hit enter to continue.
2. Navigate to the following registry key in the Registry Editor:
3. Locate the value named “ProgramFilesDir” and change the default value “C:\Program Files” to your new directory path(address).
4. Close the registry editor and reboot your system to apply the change.
5. Good luck!
PS: This tweak should work fine with Windows XP,2000 and upcoming Windows 7.