[jyl]

Buy two USB external HDDs of size equal to or larger than the HDD. Plug both into the computer. Move all files, photos, music, etc to one of the external HDDs. Set up a weekly backup to the other external HDD.
Replace internal HDD w/ SSD. Use Crucial or some other vendor who supplies the cable and software to clone your HDD to the SSD, then it is a simple remove and replace operation (no reinstalling software etc).
While you're at it, max out the RAM.