A SSD is much faster when used as a boot drive. For example my 4 year old computer with win 7 used to take 45-55 seconds to boot. With a ssd it now takes about 10-20 seconds to boot.
I play a lot of games like ME3 and MW3. When the match started I would often be last in sometimes like 30 seconds late, becuase the game has to load the level and such from the disk. Now with windows and the game installed on the SSD, the map loads in like 5 seconds and Iam normally first in.
SSDs are fast for loading and copying files, but they will not make the game play or FPS faster.
The down side is they are still pretty small, so you really need a mechanical hard drive for all your personal stuff and you need to plan ahead in reguards to what programs you want to install on the ssd.
SSDs work best on newer boards that support AHCI, so if your board does not have AHCI then it might not even be worth the trouble.
SSD'a are much faster, but I have noticed that some games don't seem to load faster on the SSD. There is a program(steam mover) which was designed to move steam games from a hard drive to an SSD, but it will work for any game(or program). This will allow you to move games onto your SSD and play them, but move them back to your HDD when you get tired of the game, or need space for a new game.
I have noticed tho that the biggest size ssd ive found what a 120gb. Im guessing i would be able to fit like 3 games on that with my od has well ?? So id have a fast os and 3 games which run faster. The the test of ym games on the 2tb driver which runs 50% slower ??
I did a clean install of windows 7. I have 8 gigs of ram so I set the Page file to 1gb. Its a desktop so I dont use hybernate so I dissabled that. That put my Windows install at about 10 gigs. My SSD is a 120 once formated its like 100gb. So that leaves 90 gb for games. Most games are like 10-15gb so that is like 6 games.
I have steam and origin installed on the D drive. That is an WD black 750gb. That is also where my "mydocs folder and such are.
I use the windows mklink command to leave steam and origin installed on the D drive but to run my favorate few games from the C: drive. This is an easy way to manage what games are on the C: and D: drive.