If you were to partition, it wouldn't do a whole lot of good, as far as I am aware you would lose all your data if you tried it now.
Besides, it wouldn't protect your games if the HD was to fail or something if they were on the same drive.
Just install them on your main (only) drive and partition, that's what I do.
Ideally you'd have a separate drive for programs, data and the OS, but that's rare.