C:\Program Files directory is considered as the default directory for installing new programs in Windows and here there is a simple and easy way(registry) to modify it permanently. Just follow the few steps mentioned below.
step 1 : Click on start then run and type regedit and press enteror simply press win+r which opens run command and then type regedit and press enter
step 2 : Press CTRL+F and find for the below key in the registry
step 3 : Then find for ProgramFilesDir. By default, the value will be C:\Program Files. Edit the value to any valid drive or folder and XP will use that new location as the default installation directory for new programs.
Enjoy this trick!!