I got the Kingston HyperX 120GB SSD for running a Windows 8 setup from OCUK, it even comes with its own 3.5" adapter. It is very fast access and boot time and with Windows 8 it only takes up 38GB on the Drive. With Windows 8 optimized for Trim if games are where you are hedging I would go this way. Windows 7 likes to buffer a lot more to the system than Win 8. In actual fact it is very similar to Vista. Vista doesn't understand Trim though. I have a version of Vista on a Sandisk 120GB I keep as reserve and that boots up in 11 seconds an the Sandisk SSD is only SATA II.
Crucials M500 are not particularly fast on boot and they are SATA III and the OCZ Vertex2 I purchased from OCUK is only SATA II but it is the Bigfoot 480GB and I boot nto windows 7 in 8 seconds. Win 8 on the HyperX is there in a few seconds. I don't even bother counting. On the Boot menu I click once and its there.
This could be down to my system as well. I have the i7 3770K on and ASUS P8 Z77V LX Motherboard with 16GB of Ram. I have only gently overclocked the cpu to 4.182GHZ and never really pushed it but I like a system that efficiently deals with its internal storage and external storage.
reducing the overhead of moving mechanical Hard drives in my system reduces heats and power, having one Data drive internal which is 3TB helps reduce power overhead as well.
My advice, get a 120GB and a decent Data drive which you can partition. Then go into your personal folders select properties and loaction on things like Music and Documents, select move And the Drive/Partition you wish to put things on. Music and iTunes etc can all be moved this way simply, which again cuts down overhead. Dowloads is another one that should be selected as an off boot primary directory to be moved. Boot drives fill up very quickly when downloading.
Hope this helps.