I am of the belief that Steam #vĀ¢|<'s up your Windows registry and bogs the computer down upon installation, so I want to know if there's a way to virtualize it?

To clarify, I want to install Steam/TF2 on my secondary HDD [D:], but without touching my new SSD Windows7x64 installation on [C:]

Since I have not found a way to make Steam portable, I thought maybe something like Sandboxie (application virtualization/sandboxing) might help, but I don't know how to get it to write to [D:] without affecting [C:]

Any thoughts?