most games aren't going to use the extra memory ... unless you plan on trying to hook multiple monitors up through your laptop the 2 gigs will be wasted .. its there to sell cards to peopel who don't look up benchmarks before buying..
side ntoe you might also use that 2 gigs if you play wow or somethign with a huge draw distance on a flying mount... but even then instances and regular play it won't make be utilised
isnt the gt 435m has more memory than the 5870? that is what im not sure about. so what kind of features that can determine which card is better?
extra RMA is on helpful with a GPU powerful enough to use it, the GT435 is not one of them. the 5870 also features faster DDR5 RAM to the slower GT435's DDR3. Nvidia stuck with the extra RAM to make themselves look better. it similar to when PC manufacturers stick 8GB of RAM with a dual core CPU, when a quad core with 4GB would actually be faster.
The ATI Mobility Radeon HD 5870 is a high-end DirectX 11 capable graphics card for laptops / notebooks by AMD. At the time of announcement (Jan 2010) the 5870 paired with GDDR5 memory should be the fastest laptop GPU (except SLI / CF) available. Technically, the chip is based on the desktop Radeon HD 5770 (RV840) with a slower clock rate.
The performance of the GeForce GT 435M is intended to be on a level of the Mobility Radeon HD 5730 in the upper middle class (in 2010). As the GeForce GT 435M features a new architecture, the performance is not comparable to older chips with a similar core count. The DDR3 graphics memory combined with the 128 Bit bus should be the bottleneck of the GT 435M. This means, that the card should be suited for demanding games in medium-high detail settings.