Which one’s better?

ATI Mobility Radeon HD 5470 / Nvidia GeForce GT 420M
Core Speed: 750 MHz / 500 MHz
Shader Speed: 750 MHz / 1000 MHz
Memory Speed: 1800 MHz / 800 MHz
Memory Size: 512 Mb / 1024 Mb

Which one is better?
Note: These are both GPUs of laptops (two different Acer Aspire’s) with a 2 GHz dual core Pentium and 4 Gb of RAM.

(speeds are guidelines set by manufacturers and may vary a bit)