I will help fill in a little if i think i can here. You want to use the ssd drive as ur main drive for yourself which would be your boot drive if so then achi mode is best for speed.
Problem i see is a different hard drive for everyone else if ssd is main boot drive then i dont know how to dual boot the same operating system. If you had vista on 1 hard drive then you vcould put everyones account on there and main boot your ssd.
Another problem if you do that everytime you boot u will have to change bios. 1 bios for ssd and another ide for other drive.
Thinking here i have dual booted alot till windows 7 and at first i had vista dual boot with it till it released full version.
OK you cant dual boot windows 7 if all you are using is windows 7 you have to have a different os for other boot and again if it is plain sata drive you will have to change bios when u change drives.
Plain and simple i dont see how you can dual boot with a ssd and a plain sata without alot of trouble period. Maybe dark or absic can help a bit more but i think they will agree what you want to do is not possiable at this time just using windows 7 only and unless you want to change bios everytime you boot. Most ssd drives are to small unless you get a 256 gig or bigger that way u can make different accounts and not mess with bios set it to achi and let it go.Here is a link to help you out read and go from there. They say you need different keys for dual booting windows 7 hope it helps.
http://www.tomshardware.com/forum/7441-63-dual-boot-copies-windowsYou will still have the achi problem in bios with the ssd drive.