I use an 80GB Intel mSATA SSD in an IDE adapter in my old Dell D610 running XP. The Intel SSD Toolbox works fine and allows me to TRIM the drive when desired. mSATA to IDE adapters are available on eBay and from Addonics and SinTech websites.
It's much faster than any hard drive, uses less power, is totally quiet, and much less heat. And, of course, you can use whatever size msata drive you want.