(I'm a structural engineer.) Autocad doesn't gain much with a fancy GPU, but if you do a lot of rendering then that would help a little. So for everything but rendering an ordinary laptop will work. Autocad needs a lot of ram so for sure get 4GB, and get the fastest processor you can get. Revit is pickier than Autocad but still works fine on my Dell business class laptop. The problem with Revit can be getting good drivers for the video card.
Depending on your price range you can get a reasonable laptop at BestBuy or Dell for between $500 and $1000. You can get professional quality (business) notebooks from Dell, HP and Lenovo but they will cost about as much as a Macbook Pro. Many of these fancier notebooks do come with a fancier GPU. A Macbook pro is fine, just be sure to get enough ram and load Win7 on it, but when you get into that price range it is no better or worse than a business class Dell/HP/Lenovo machine.
If you are going to do a lot of revit or autocad with large models, then you might look for a notebook with more than 4GB of ram and get Windows 7 64bit version. We run Win7 64bit on our desktops at work along with 8GB of ram.