Just don't defragment it. Ever. You don't need to, Windows should take care of the only thing that an SSD needs (and that is Trim).
However, to be sure that Windows did indeed detect your SSD as an SSD and set trim on:
fsutil behavior query DisableDeleteNotify
It will give you one of two results, either a 0 or a 1. A zero indicates that TRIM is enabled correctly, a one means that it is not. If you have a TRIM-compatible SSD, but find that Windows 7 hasn't enabled the command, you can easily do so by running this command:
fsutil behavior set DisableDeleteNotify 0
Again, Windows should automatically detect an SSD and set this for you (7 and up) Older versions of Windows, you're probably going to have to do some gymnastics with 3rd party software or tweaks to get it to work right. Found one
here in case you need that.