I wouldnt get either of them, if you want them for playing games.
Dont get shared video memory, get Dedicated video memory.
Look for graphics along the lines of
ATI Mobility Radeon X800 (XT)
nVidia Go 7400
nVidia GeForce Go 6800 (Ultra)
256MB NVidia GeForce Go 7900 GS
256MB ATI Mobility Radeon X1800
and if you can swing it get a 7200RPM hard drive, Trust me its worth it
*HYPERMEMORY AND TURBOCACHE
With the advent of PCI Express, ATI and nVidia have developed technologies that allow the use of system memory as a buffer for graphics data, basically extending the memory of the dedicated GPU itself into system memory. The nice thing is that this can offer a healthy and very inexpensive performance boost for chips that would otherwise be painfully crippled.
The problem is that system memory is almost always slower than dedicated GPU memory, so it's no substitute for having dedicated memory.
Worse still, low-end parts that use this technology are frequently marketed in a misleading fashion. For example, newer Sony S-series notebooks use GeForce Go 6200s that list as having 128MB of video memory when in fact they only have 32; that 96 is shared. Likewise, there's been a lot of confusion regarding the amount of actual memory on the ATI X300s used in Dell notebooks.
It's my understanding that the major culprits of this are the GeForce Go 6200, 6400, and the X300. But while the X300 may be marketed as having HyperMemory, the GeForce Go parts tend to gloss over their use of TurboCache.
One great thing about HyperMemory over TurboCache is that it's almost entirely software, so most ATI cards, with some tweaking, can use it, though the performance improvement is largely minor.*
