i did a little research about this a few weeks back, bcoz my sister-in-law who's doing interior design was considering to make the switch... She uses the exact three applications a lot: Photoshop, AutoCAD and 3ds Max...

From autodesk's webpage listing 3ds Max system requirements:
"Note: Apple(R) computers based on Intel processors and running Microsoft operating systems are not currently supported"

The same thing isn't stated in AutoCAD's system requirements.

If you read up the Autodesk forums, there are users who have managed to run both on bootcamp, but it's not as problem-free as running it on a windows based PC... They don't recommend running these programs via Parallels/Fusion etc... Google "bootcamp 3ds max" and "bootcamp autocad", read up, read up, read up, before deciding whether to go Apple... If you decide that you're willing to go through the trouble (and risk of not being able to run these apps properly), don't buy the mini/macbook... It'll take ages to render your designs, that's if it manages to run the programs in the first place...

Photoshop can be used without problems, as there's a version specifically designed for macs... There are alternative CAD/3D applications for the mac, but they may not be as fully featured compared to autodesk's products... If you're already comfortable with AutoCAD & 3ds max, you may not be too keen on learning new programs either.... So yeah, decide carefully... It's good that you're asking around and doing research, at least you'll be well aware of what to expect....