As the size of hard drives increase, more people are using partitions to separate and store groups of files. XP uses the C:\Program Files directory as the default base directory into which new programs are installed. However, you can change the default installation drive and / or directory by using a registry hack.

1. Start
2. Run
3. Type regedit
4. Go to this directory:
   

   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion

5. Look for the value named ProgramFilesDir. by default,this value will be C:\Program Files.
6. Edit the value to any valid drive or folder and XP will use that new location as the default installation directory for new programs.

And that’s it! I recommend this after when you’ve formated your Windows, this way you have a clean and fresh install and you’re sure that there wouldn’t be any trouble with previously installed applications.