No, one OS one install. An SSD is wasted if used as a cache for Intel RST. Install the OS on the SSD BEFORE you attach the HDD to insure that the SRP (system reserved partition) ends up on the SSD. Then attach the HDD and configure it in disk management.
Use the SSD for you OS and most commonly used programs/games, other programs/games on the HDD along with data.
Get as big an SSD as you can afford, get it on sale -- prices change constantly, watch here: http://www.logicbuy.com/categorydeals/computers/hard-drives-ssd
Then optimize your drive: http://thessdreview.com/ssd-guides/optimization-guides/the-ssd-optimization-guide-2/