Here's a method for best of both worlds
Install OS to SSD
Move all windows default file locations to HD
Move e-mail storage to HD
Install 1st game Ya wanna play to SSD - to C:\[Game1Name]
Install 2nd game Ya wanna play to SSD - to C:\[Game2Name]
Install 3rd game Ya wanna play to SSD - to C:\[Game3Name]
Then let's say you wanna play Game 4 but worried about space and ya not playing Game 2 that much lately. Open Explorer and cut / paste the folder [Game2Name] from C:\ (SSD) to D:\ (Hard Drive).
Install game 4 to SSD
If ya get nostalgic for game 2, just cut / paste it back
Back when I had my Palm Treo, we used an app called PowerUp if I recall correctly or something like that by which we'd designate what programs we wanted to store on a SD card instead of main memory. When ya clicked on a program icon where the program was stored on the SD card, PowerUp would cut / paste it from the SD card into main memory, and when ya cloised it would put it back, all transparent to the user. Why no one has developed this simple program doe OC's w/ HD / SSD combos is beyond me.