Oh wait, you want to set your install directory to the hdd by default?
To change the registry, follow these steps assuming your storage drive is D:
1. Start Registry Editor by entering “Regedit” in the search All programs.
2. Locate the following:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion
3. Right click on the value named ProgramFilesDir & change the default value C:\Program Files to the path you want to install all your programs in. "D:\program files" without the quotes.
If you are using a 64bit o/s then change the entry below it to
"d:\program files (x86)" without the quotes
4. Click OK and Exit.