The trouble you are going to have is that the cards use drastically different drivers which will probably conflict with each other on the same machine.
What you might be better off doing is running the gaming card under windows with only its drivers installed, and setting up a linux based OS for you workstation apps with only the workstation drivers installed. Or you might look into soft modding a gaming card.
I am running Windows XP 32-bit right now and i have 2 x ATI x1300's & an Nvidia FX5200 all running at the same time... it's my work machine, it's a Dell...
Time of this report: 1/15/2010, 11:35:27
Machine name: RI1Y4NYD1DSK
Operating System: Windows XP Professional (5.1, Build 2600) Service Pack 3 (2600.xpsp_sp3_gdr.090804-1435)
Language: English (Regional Setting: English)
System Manufacturer: Dell Inc.
System Model: OptiPlex 745
BIOS: Phoenix ROM BIOS PLUS Version 1.10 2.3.1
Processor: Intel(R) Core(TM)2 CPU 6700 @ 2.66GHz (2 CPUs)
Memory: 3070MB RAM
Page File: 886MB used, 8150MB available
Windows Dir: C:\WINDOWS
DirectX Version: DirectX 9.0c (4.09.0000.0904)
DX Setup Parameters: Not found
DxDiag Version: 5.03.2600.5512 32bit Unicode
DirectX Files Tab: No problems found.
Display Tab 1: No problems found.
Display Tab 2: No problems found.
Display Tab 3: No problems found.
Sound Tab 1: No problems found.
Music Tab: No problems found.
Input Tab: No problems found.
Network Tab: No problems found.
It can be done except the forceware may need a hotfix so that it won't conflict with the ATI card since nividia patched so that people couldn't use multi-card for physx but that don't stop every one. Some even keep their 3DFX voodoo2 cards up in running even under Win7 32 with other cards using the patch and pass through cable. For your case you need to select for each game or CAD app which card to use (GPU). Vista can also use multicard but one will need to patch so start looking around on other forums about using physx with ati cards (multicard) to find what you need.