An SSD is by far the best upgrade I made to this laptop.
I now have two HDDs in here, one where the optical drive used to be. I can gladly sacrifice the ODD for the huge speed increase! Boot up with Windows 8 is about 15 seconds, and I am not light with my boot up programs:
ESET Smart Security
Malwarebytes Anti-Exploit
Skype
Bvckup
KeePass 2
TeamViewer
Dropbox
F.Lux
CintaNotes
Greenshot
The main advantage I've found with the SSD, is even though it does still take another ~15 seconds for all those apps to appear, I can carry on doing other things whilst they load without any slowdown. Having a large amount of startup programs is no longer such an issue, and 8GB of RAM means there's plenty of RAM spare.