The X1400 is more for those who game casually or just use the notebook for multimedia functions that doesn't require lots of GPU power. The 7800 GTX Go is for the hardcore gamer that must have absolute power in their laptop. It really depends what you need and what those laptops come with. If you're looking for a desktop replacement, then the 7800 GTX Go definately will do. If you just need something that will game pretty decently and is light on the battery, the X1400 should be just right.
ATI is so behind nVIDIA in the mobile market now...the highest they have is the Mobility Radeon X1600 XT while nVIDIA has the GeForce 7800 GTX Go. It's time for ATI to come out with something like the X1800 or X1900.