I'd says the 7200 rpm drive is about 1800rpm faster. I wouldn't use a 5400rpm drive for gaming or programs. However, they are good for storage drives.
As Hawkeye has said above, a 5,400 rpm hard drive is going to be just fine for storing files long term, but they are pretty slow even when compared with 7,200 rpm hard drives. Your primary storage is the slowest part of your whole computer, so the faster you can get that the faster and more efficient overall your entire computer system will operate.
From my experience, platter density seems to make a bigger difference than 5400rpm vs. 7200rpm.
Be aware that the 2TB Seagate drive comes in two versions. The faster one has 2 platters, while the slower one has 3.