*some major generalizations to follow, but it`s a fair rule of thumb to use*
Immediately off the top of my head, I`d go x800 b4 a x500 in any series. 9000 to 8000 are fairly close if u compare 8000 to 7000, as we witness the slowdown of graphic tech.
500/400/300/200 are, to me, stripped 600s - which are mid-range cards. Sub 600 cards are generally considered multimedia and very minimal games.
Anything above 600 would be capable of gaming by intent.
Of course the M versions aren`t quite up to the regular PCI/e slot versions u`ll get for ur pc, as they are of course for Mobiles, with power considerations.
If u want to game, 8800, if u want to multimedia, 9500.
Linkage to the actual laptops may well sway the decision mind u.