In Windows Xp the default location where the applications are installed is located in C:/Program Files. Sometimes you can run out of space in C: drive and it become impossible to install the programs. But there is a registry tweak which can let you install the applications in different directory of your choice.
Run the Registry editor by typing regedit in the run command box and go to
Just look for the value named ProgramFilesDir. You will see that this value is shown as C:\Program Files by default. Now edit this value and add the location where you want to set the default installation directory. From now onwards XP will use this location as the new default installation directory.