I'm finally planning to make the leap from HDD's to SSD's. I have a 150 GB Velociraptor as system and high-end game drive right now, but the HDD-SSD performance charts just make me cry. I'm planning to buy an OCZ Vertex 3 (seems to be the new fastest kid on the block).
And now I'm wondering - does it make sense to install the OS on the SSD? With the steep prices, every GB counts and 64bit Win7 + paging files weigh quite a lot. I really don't care if my Windows boots in 10sec or 5sec, since I do it once a day - wouldn't it make more sense to install the OS on a conventional drive (my Velociraptor, for example) and leave the SSD for my games because I use them all the time?
Having the OS installed on the SSD provides far more benefit than just start up times. Every single OS action involving that drive will be faster including paging and the loading of applications.
If you were to use the SSD for your games you'd only potentially see an improvement. It's largely down to how the game has been implemented. The game might start quicker, it may load saved games faster but you're unlikely to get increased framerates or anything.
For this reason I'd use it for the OS. It will have a greater widespread performance improvement for your system.
Typically we find that the vast majority of users install the operating system and a few sotware applications or two of the most played games on a solid state drive while everything else is stored on a hard disk drive. The reasons for this is the high price and low capacity of ssd's. SSD's will start a game faster and might bring up a map or a chart quicker, but it will not improve fps.