Windows 7: Change default hard drive

Hi. I have two hard drives in my computer. One is 320GB and it is almost filled up. I also have a 1TB hard drive that I bought recently. All the programs I install automatically choose the C drive (320GB). How can I change the default hard drive to the A drive (1TB)? I know you can just change the install directory when your installing the program but it would be a lot easier if it automatically chose the A drive. Some programs don't even give you a choice where to install it.

If your 320 GB drive is filled up with user data, like pictures, songs, etc, just move them over to your new drive and use that for data storage. If the 320 GB drive is filled up with apps and games, you could either uninstall what you don't need, or clone the 320 GB to the 1 TB drive.

OK that helps but it doesn't answer my question.

Go to registry editor:
go to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion
You'l see programfilesdir (86) and programfilesdir. Change the location specified in each to your desired location.

"Changing the default file location can have undesirable ramifications."

Undesirable ramifications???

Yes, in rare occasions some programs expect to be in the default location, so if the install path is changed, they may error.

Ive written this tutorial.

OK I changed the registry. Once I started my computer this morning I find that about half of my shortcuts on my desktop have disappeared. Is this apart of the "undesirable ramifications" or is it something else?