FEMM looks good. I am checking into it. CAE linux looks very nice as well. I am trying to set up a virtual box to run a Ubuntu install for the software.
Try a dual boot its more effective and i know for sure CAE linux 2011 is quite stable because i am using it except for the screen flickering which can be changed by making a few changes to your grub... its your wish anyway..
A few years I have used getdp, which you can find on the site http://www.geuz.org/getdp/ . I used it for 2d and 3d calculations. It takes a little effort to learn, but it works really well and is free AND available for Windows/Mac/Linux.