you can change the default installation drive and/ or directory by using a Registry hack.
Go to:
1.Start > Run
Type regedit
Go to this directory…
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion
3. 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.