Change The Default Location For Installing Apps

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.

Run the Registry Editor (regedit)and go to
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion
Look for the value named ProgramFilesDir. by default,this 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.