An SSD has the least advantage over a good HDD with large sequential files. Where the SSD really shines is with small, and especially random files. Obviously, the OS, and programs, as well as any swap and cache files should go on the SSD. With leftover room, put on the files you use most, or are currently working with. If they're not needed for some time, send them back to the HDD.
QFT
On my desktop systems OS, Programs, Pagefile etc goes on the ssd. Games, Docs and any other files go on HDDs. On my dual drive lappy the only exception is that I put my personal docs on the ssd as well, but thats only 20gig of files.
You put your games on the HDD? Won't they see a pretty large decrease in load times if they were on the SSD?
I used a Gskill falcon ssd for game installs for a while and didn't notice much of a difference in load times. It was faster but not worth loosing the convenience of just having a large HDD to put all the game installs on. Game loading is mostly sequential anyways and the HDD I use tops out at 110 - 120MB/s.
If you have a decent amount of ram 4gb+ then I guess I can see how the SSD doesn't really help that much with games.