While the rule of thumb for SSDs has been to never defrag them to avoid excessive writes, over time, reports have been popping up saying they do need an occasional defrag (but nowhere near as much as a HDD). I have yet to defrag any of my SSDs because the fragmentation level is way too low to worry about or, in the case of the boot drive in my desktop rig, the fragmentation level stays at 11%, which is not enough to worry about as long as it stays there (I've been running pretty much 24/7 for almost two years).

As far as defragging HDDs on Win 7 goes, I've found that Win 7's native defragger works as well and usually faster and better than third party defraggers. In fact, one of the ones that was popular with XP, Defraggler, was considerably slower and managed to corrupt one of my HDDs beyond repair other than a reformat (thank God for backups!). I have Win 7's native defragger set to defrag as necessary during the wee hours every Wednesday morning on my desktop computer (my notebooks only have SSDs for system and storage) and, when I was still bothering to spot check on Tuesday, I never saw a HDD go over 1%; almost all of the time, they were still 0%.