You have not mentioned what version of Premiere.
- I did all my HDV editing in Premiere Pro 4 without of course MPE. I think you will be able to get along with simple HDV editing without MPE Hardware Acceleration, but you may have to render the Timeline in some cases.
- I love my Z68 (1st place in Sandy Bridge PPBM5 scores with CS5.5) and of course I have just simply turned off the HD3000. Either board will support MPE software and there will be no difference as the CPU powered MPE will be identical
- You have a slightly wrong conception of a Graphics Processing Unit (GPU). If you want to see the screen you need a GPU. If you want the GPU to be used for other than displaying the screen like for MPE hardware acceleration then you need a CUDA card. The on-chip HD3000 is a GPU on the i7-2600K chip but it is not CUDA based
- Yes both use the MPE hardware acceleration of CUDA based cards. CS5.5 does use do much more processing in the CUDA based GPU if it is available than CS5 did.
- .After effects does not currently use any CUDA acceleration. From Adobe on GPU support for Affter Effects: "On both Mac OS X and Windows®, display card drivers that support OpenGL 2.0 or later are required to take advantage of OpenGL support in After Effects."
- Photoshop requires a GPU with the same OpenGL as After Effects. There is no benefit from a CUDA based Graphics Processing Unit
See this video for details of what Premiere Pro does with the GPU:
This article goes into more detail than that video.
> After Effects doesn't use the GPU at all, is that correct?
See this video for details of what After Effects does with the GPU: