An ssd would be a huge upgrade. It's the biggest upgrade you can make. Doubling the RAM would be huge if you're going from 2Gb to 4GB, it would be noticeable if you're going from 4GB to 8GB, but it would hardly ever be noticeable if you're upgrading from 8GB to 16GB.
Unless you are just doing some seriously intense computing, rendering, editing, or a silly amount of multitasking, you will not notice the difference between two i7s.