Just change the place that programs are saved by opening the registry editor -- type regedit in the start button search box and select the program. Then navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion the change the key ProgramFilesDir from C: Program Files to whatever the drive you want in a Program Files directory. If you are using the 64 bit version also change the ProgramFilesDir (x86) key similarly.
What about all the other data values? Several other Keys have the path on C:\ drive. Should I leave those? Also when I go in to change it can I just swap the C for a B (the name of my HDD)?