On the bench this morning was a 2011 iMac, 27" that required an SSD fitting. As you can see in the photo we have already installed the OWC 240GB SSD, its fitted to the right side of the casing and fits underneath the optical drive, which we are just about to fit.
The SSD gives the iMac a great performance boost. We are able to leave the hard disk drive and optical drive both in the iMac. The 1TB hard drive can be used to store video footage, music etc whilst the SSD stores the operating system and main applications.
OWC make high performance Mac upgrades, SSD, RAM and lots of other parts, see http://www.macsales.com/ for further details. Ubertechs Ltd are a UK supplier of OWC components.