My machine started slowing down, it would take an age for firefox to load, word (yes I know a microsoft product on a mac - berate me later!) took forever and generally becoming easier to reverty to pen and paper. Tried cleaning up and defragging, removing duplicates, even took music and films off my 120gb drive but poor thing was just too old and cream crackered (knackered)
So ordered the kit from this site.
Repair was really easy, was a little nervous, but I had spent a good time backing everything up, I didn't want to do a clone just in case it wasn't the drive totally, plus there is something quite nice about having a fresh install. I set everything out on the table, took a couple of hours off work when everyone else couldn't contribute their opinions on what to do next. Grabbed a coffee and loaded the guide on my ipad.
I found laying out the screws in the position they came out helped putting it back a lot faster. Kinda like a pre-made jigsaw. Spend some time thinking about the apps you have, serial numbers, etc. Ive now got a very easy to restore process because of that.