I'll be joining the future and getting an SSD sometime in the next month. And I may even do a reformat and make sure that all my backup data goes on my 600GB spinning drive rather than on the nearly full 350GB spinning drive it's currently on. Then I'll have Windows and all games running from the SSD and have all my backup files on a spinning drive (until I get around to buying another SSD).
And, someday, I'm going to build a small server for my house, and use that to stream steam games to my other devices. Ahhh, the future is great!
I just did a complete reformat with my new drive... now the OS and any games are installed on the SSD, and all media files and data that I want to keep are on my 600GB disk drive.