If you are going to be using CAD software, you should look into the actual models made for that like the Lenovo W series, HP Z Book, Dell Precision, etc.. that come with a Quadro or FireGL video card and proper drivers.
If you are doing actual work on the systems instead of just learning, you will likely need to run the software on a certified computer for the programs or the work may not be accepted. http://searchitchannel.techtarget.com/definition/ISV