Yeah...they're pretty similar, but for a hundred dollar difference, I'd go with the Toshiba. Graphics card is hard to upgrade later, but ram is easy to. I don't like the AMD processor so much though, it's only got 1 Mb of L2. However, it should still be fine. And you can also upgrade the processor too, it's just a little bit more work.
Also, I don't like Gateway's customer support.