jaguarskx :
The performance of the NVS 5100m is between the Intel HD 4000 and HD 4400; closer to the HD 4000 though.
It is decent enough to play games on low settings that are not very demand with okay performance.
I've got a friend with a decent laptop with the HD4000 graphics and she can't get skyrim to play any higher than 25-30FPS on low details @720P. With my Elitebook 8540P, I get 30-45FPS @720P with everything on high (medium for shadows) and HD texture pack, 2xAA, 16xAF on stock Quadro drivers (about to try forcing Nvidia 330M drivers because they are almost the same card)
The NVS 5100M is weak though, not arguing that, but it's definitely an improvement over HD3000,4000,4400 graphics/performance. Not a large upgrade, but still better. I can crank games like Bioshock to native resolution (1600x900) with 8xAA, 16xAF and get a rock solid 35FPS. Fallout 3 is running 720P, HD texture pack, all high/ultra details, 4xAA, 16AF, 4x supersampling and all graphical sliders up and still get 45FPS in all outdoor areas (drops to 25FPS when there are explosions during firefights).
I'm eager to see what the Iris could do though, as it should sip battery power, but also provide modern low end dedicated GPU performance, eclipsing the NVS 5100M. The only benefit these Quadro cards have is in 3D graphics programs, which is what it's designed for in the first place and gaming shouldn't be a concern.
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Also, just noticed one of the OP's questions, your first gen i7 mobile processor, while slightly slower in clock speed compared to the single core Pentium you mentioned, it is overall better in every way. A single core processor still has uses, but for even general computing, a dual core is the bare minimum you should be looking for. Our i7 processors, while very good dual cores, have hyperthreading technology, allowing for 2 operation threads per processor core, which kinda makes it work like a quad core, but not quite as effective. I believe the Pentium has hyperthreading as well, but still not quite able to match the pure computational multitasking of a multicore CPU.
Sorry for all the words, I just like to explain myself thoroughly on internet forums.