Edit: I'm assuming Windows 7. Some version of Linux may fit within only 16GB, but if you lose TRIM support, the drive will begin stuttering sooner or later unless you run garbage collection utilities on it.
why can you not install windows on a ssd that is smaller than 64gb? what about the ocz vertec 32gb. The os is the only thing that will be installed on that drive, everything else, games, office, photoshop will be installed on my raptors in raid0, and i have another drive for storage
i may be missing th point so please explain further
You might cram Windows 7 into 32GB; I'd suggest loading programs there too though. It will partly depend on how much tweaking and cramming you want to do. For example, if you use Steam, it installs to C:, and I've not yet found an obvious way to make it use another drive.
The OCZ vertex 2 "E" is best rated and there is a 90 G version. Read the reviews on these SSDs. New Egg and Amazon offer good deals periodically. Note that better, faster SSD drives are coming out soon and Sata III ssds will be the future. You may want to buy a cheap drive for now like a 60 G or 90 G drive while you wait for the new SSD improvements.