CAE/SPICE for Slink/Potato

[Bill]

Hi all,
    I'm trying to model a circuit, actually a high powered inverter and I'm 
trying to find a simulation program to do it. All the W9x programs I've found 
so far are demos, not able to handle all the components. Does anyone have any 
idea as to where I can find sims for Linux and their accuracy? Has anybody 
used any of them?
   Any input appreciated.
Thanks
Bill Cooper