I successfully upgraded my HD last weekend. My current drive is about four years old and gets daily use, so it's just getting to that age where it could fail. I wanted to replace it with a fresh one, and I got a larger one (250GB => 500GB) while I was at it. The whole process was inexpensive and easy. I bought a new 2.5" 500GB drive on eBay made by HGST, formerly known as Hitachi. This brand ranks high on reliability in published tests. I also purchased an external drive caddy on eBay to run it while I copied all the data from my current drive. This caddy has three cables: power, USB, and eSata. The eSata port on my laptop provides data transfer at a higher speed than a standard USB port. And I needed a caddy with a separate power cable because the current draw on the new drive is higher than what you get (0.5A) from a standard USB port. I downloaded Macrium Reflect software, the free version for personal use. It cloned my new drive from my old one and formatted the new drive to maximize all the available free space. The cloning operation copies all the partitions and system files needed to make your new drive bootable with all the same data on your existing drive. The cloning operation took one hour to complete. Then I just removed and replaced my existing drive with the new one. I had to reboot Win7 a couple times to get the drivers loaded, but that was it. I'm keeping the existing drive as a spare backup. I can run it from the caddy and access it like an external USB drive, or I can put it back in the laptop if the new one fails for any reason. I love it when a plan comes together.
Yes, the main issue here is to clone disk drives here correctly, but at the time of writing this I can recommend you to upgrade drive to SSD really for much better speeds anyway, what do you say ? I would say it's a must nowadays.