Intel HD Graphics 3000, AMD Radeon HD 6490M with 256MB GDDR5
or
Intel HD Graphics 3000, AMD Radeon HD 6750M with 1GB GDDR5
Which one would be better to run autocad? I'll be using it for engineering school this fall.
Would it matter?
The new integrated graphics stuff has the potential to eventually outperform discrete graphics cards, but it doesn't seem to be there yet. As of now, it seems to be roughly equivalent to a pretty low-end graphics card. So I wouldn't recommend the HD Graphics yet.
And in general, I would recommend staying with a minimum 512MB graphics card, so I'd say the HD 6750M is a better choice. Autodesk's specs say 128MB minimum, though, so the 6490M might work well enough, especially since you intend this as a student computer. But if the cost isn't prohibitive, I'd say go with the HD 6750M.