My 500GB hard drive was maxed out.
It was so much easier than I anticipated. Well, if I had been on my own there is no way I would have had the confidence to try this job. The explicit and simple directions along with the great pictures from iFixit made this job a snap. I bought the 1TB hybrid drive from them along with the tool kit. It had everything I needed to do my HD replacement. I understand how computers work in general but I'm not a take apart my laptop guy. iFixit provided me with the right tools and confidence to give my MacBook Pro new life.
For the novice (like me), the order page on iFixit where you have a choice to just buy the hard drive or the tools and old hard drive enclosure isn't super clear. I was a little unsure if it included all of the specialty screw driver tips I would need to take apart my MacBook Pro. Fortunately the group at iFixit was thorough and I had everything I needed. For me it was a mystery until the order arrived and I got into the project.