That's Fast. Incredibly fast. But, this method isn't as fast as it could be, as it is limited by the 150 mb/sec transfer limit for SATA. (the i-RAM device uses SATA 150 only)
SO....here's the idea. Using a motherboard with 8 DDR2 RAM sockets (I can't find any Intel motherboards that use this, but I am looking) you would load it with 8 2GB DDR 2 memory modules. Right now, newegg has 2 2GB modules of ADATA DDR2800 memory for $50 after rebate. So, for a total of 16GB it would cost $200.
As I can't find a suitable motherboard, I can't determine what it would cost. But, I would guess the motherboard might cost $300 more than normal.
Total cost ~$500.
Using a boot loading program that sets up a 12GB RAM disk, you would copy over the entire OS partition, stripped down to size with nLite. About 4 GB of the 12 GB RAM disk would be used.
Then, you would have a series of boot loading options that gave the means to copy over 8GB of data for the game you are planning on playing. You'd have to choose at boot what game you want to play.
