tfishell: I'd imagine Dune 1 & 2 would be shoo-ins unless they don't play right in DOSBox. I don't know about the non-DOS titles.
I own every Dune game so I decided to check how they work on Windows 7 (32-bit).
Dune 1 and 2 (both CD versions) worked flawlessly in DOSBox.
Dune 2000 had a little issue with the installer - the default folder was Dune2000 I've changed it to Dune 2000 (with a space) and the game wouldn't run. I reinstalled it and used the default name it ran fine out of the box. I tried to install widescreen patch and got it to run with 1366x768 resolution without any problems. And man, it does look good now!
I couldn't check Emperor because my friend has my CDs but I should get it back soon (I'll test it then and let you know)
I refuse to check if Frank Herbert's Dune runs fine because I refuse to acknowledge that this game exist ;P If I ever end up in gamers' hell I'll be forced to play it over and over again.
On the side note: even though I have them I would buy them in a heartbeat if they appeared here.