As the size of hard drives increases, more people are using partitions to separate and store groups of files.
Windows XP uses the C: Program Files directory as the default base directory into which new programs have 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_MACHINESOFTWAREMicrosoftWindowsCurrentVersion
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.