IMHO,the graphics chip either tends to be soldiered into the motherboard and even if it is a removable module they are darn hard to get hold off. Hence I always try to get the best graphics chip I can afford if I intend to get a notebook for any sort of relatively modern gaming. Things like the CPU,RAM and hard disk on the other hand can be upgraded usually.
Looking at the specs of a G102M it looks very similar to the 16 shader version of the desktop 8400GS:
http://www.notebookcheck.net/NVIDIA-...M.16313.0.html
http://en.wikipedia.org/wiki/GeForce_8_Series
A PCI 8400GS does not seem to run the The Lord of the Rings Online very well:
http://forums.lotro.com/showthread.php?p=3979063
The HD4570 would be a better chip if it was the DDR3 version but the Acer seems to have DDR2 RAM.
If you intend to keep the notebook a few years then I would go for a better graphics chip.