I put a 250GB SSD in my 2008 laptop at the same time as upgrading to Windows 8.1.
So glad I did, as for £100 it saved me spending £600 or more on a new one as I wouldn't see any gain in performance for day to day usage over what I've now got.
I bought the Samsung 840 Evo
http://www.amazon.co.uk/gp/product/B00E391OX6 which gets very good reviews across multiple sites.