Install Windows on the SSD. Don't use SRT caching. Intel SRT caching maximum size is 64gb so you'd be wasting some of your SSD's space by caching. Install Windows on your SSD. Use any additional space on your SSD (leave some free room though) for some app(s) that you use a lot.
+1 he basically said it all. You've got a 90 gig drive; please use all of it and don't waste it on SRT. If you ever wanted to use SRT, you could get an SSD like the Intel 313 series which are designed for caching. If you want to learn more than check out this link: http://www.intel.com/content/www/us/en/solid-state-drives/solid-state-drives-313-series.html