Hey, if he uses OpenGL programs - buy quadro, but if he uses Direct3D software - buy gaming card.
for AutoCAD - quadro 600(or similar priced FirePro) will be enough
for 3ds Max - quadro 4000 and geforce 460 together will be enough
those are enough for most users, but ask him about his previous rig and if it was enough for him.
AutoCAD uses OpenGL as I know, so Gaming card will be useless(gaming cards have blocked true OpenGL performance, or pro cards have somehow accelerated, so difference is big)
3ds Max uses Direct3D, due to this good gaming card should be enough, but now and then he'll encounter a lot of crashes(I'm 80% sure you can solve this by installing Quadro driver(you can search how to)), and for this you should buy Quadro 4000, quadros below it are useless and above it costs too much, so also buy cheaper Geforce card, then SLI them(compatible ones) - you'll basically get faster Quadro card(especially good for GPU rendering)
For monitor - it should be good quality one(e.g. display good quality images, have good contrast ratio. just check pro. monitor http://www.necdisplay.com/p/desktop-monitors/pa301w-bk
; then compare much cheaper monitor to something like this)
and, as someone said, buy 16GB memory, some people even have 64GB, but that much is useless, that can even slow down performance of PC.