I want to get a solid state drive. I have a Macbook Pro, 15 inch, mid-2010. It has a 320gb spinning drive. The drives I have been looking at on Crucial.com are only 500gb. Since my Mac is 5 years old already, is it worth the bother and money to put in a new drive? It's in great shape besides running hot. Or.. instead of upgrading to a 500gb solid state drive, could I use an external drive? Or would that just slow everything down to a crawl?