5 - 30 minuten
My origional HD was an 80 Gig and filled to the brimm from my IPhone sync. Pictures, movies, music etc. made my MacBook sluggish and essentially unusable. I couldnt even download updates because there was no room left!
Used Super Duper to clone the drive just as IFixit said and woke up the next morning and started the install process. I had the IFixit video going on my desktop as I went and everything went increadibly smooth.
Get the Upgrade Kit, you will thank yourself later. The Laptop screws are many different sizes so I made squares on a sheet of paper and labeled where each group of screws went to keep them straight. The adhesive on the HD can stick pretty hard, be gentle when prying the ribbon up but it will take some force.