S i X h E a D { ? }

NT/W2K/XP's default directory for installing applications is the \Program Files folder (at least for English language version of NT/Windows 2000/XP). To change the default application installation folder:

Hive: HKEY_LOCAL_MACHINE
Key: Software\Microsoft\Windows\Current Version
Name: ProgramFilesDir
Type: REG_EXPAND_SZ
Value: C:\Program Files default

Please note that some programs ignore this registry setting.

credit: windowsnetworking.com