Installing an SSD Without Re-Installing Windows
"Installing a solid-state drive is one of the best upgrades you can make to your computer, but migrating your Windows installation to a small drive can be tricky, because your data won't necessarily all fit on the drive. Here's how to install an SSD without reinstalling Windows from scratch."
I for one am very happy installing a new hard drive (or SSD) doesn't require a re-installation of Windows. There are a lot of ways to do a drive swap, but this Lifehacker article is by far the most detailed I've seen. If you're pondering moving to an SSD, it's worth a read!