The 6920g has a better GPU, the 8730g has a faster CPU.
The 6920g has a 16.4" screen, the 8730g has an 18.4" screen.
The 6920g has an older 65nm morem, the 8730g 45nm penryn.
The 6920g has a cinedash multimedia panel, the 8730g has a volume touch slider.
The 6920g has a blu-ray drive, the 8730g has a DVD RW.
I would like to know if i would be able to notice any difference between the T5750 and the T6400; or if the £20 cheaper 6920g would be the best route to go.
I meant the 8730, and they actually have the same VRAM as for the type of VRAM the 9300m GS has DDR3 and the 3650 has DDR3
I'm not sure who keeps convincing people that VRAM is the all important factor for graphics cards The only time it should be a deciding factor is when you are comparing two of the exact same graphics cards.
The 9300M GS in question is an entry level GPU that is barely a step above an integrated solution. The HD 3650 is a mid-level card that will provide a much better experience for the end user. This is not a question about which has more VRAM or of what speed. This is all about the internals of the card and the HD 3650 is superior to the 9300M GS in just about every way.
Keep in mind that VRAM is often used as a gimmick by manufacturers to get more money out of unknowing consumers. They put tons of VRAM on weak cards which thus convinces consumers, who don't go and do their homework, that it is a better card. Hardly ever the case.