you can download the games to your HDD and install them on your SSD if you have enough space for them.
I usually use my SSD for
- the Operating system (win7) and all drivers
- tools that i want to start fast (my development tools like visual studio)
- some games
i use my HDD for:
- download folder
- music & videos
- backups
- some programs that don't need to start fast
i "only" have a 120gb SSD so i had to copy some of my games to my HDD because I was running out of space.