I use Linux.
I have an SSD of 128GB (Sandisk Ultra Plus). I don't use all of it for the operating system, just 18GB. And I use a 1TB external hard disk for the /home with the users.
So using LVM I have cut 40GB from the unused part of the SSD for 2 small virtual machines with WindowsXP and Win7, and mounted this partition under /home/user/Virtualbox VMs/
I've moved all the files into the SSD and now the Windows VMs run from SSD.
Well, what a boost of performance!
It's like they run natively.
Linux has lot of useful tools for doing everything with your disks. With LVM you can cut, enlarge, shrink part of the SSD to use for whatever you want.
And there are tools to use SSD as cache for mechanical drives.
If you need Windows? Ok, if you're not a gamer, just into virtual machine running from SSD you'll not miss performance.