Interesting.
I'm not a gamer either, but I run some calculation intensive Fortran programs and spreadsheet macros at work, but would like to be able to do it at home.
What would you recomend?
It sort of depends on how complex and how much. If you're satisfied with the speed of your computer at work, I'm going to assume it's a couple years old, then just about any computer based on Intel's or AMD's mid market processors would probably be more than adequate.
I've been partial to Dell for years now. My main computer is due for an upgrade though (I want to do some video processing of the video I capture as per above posts). I'm really leaning towards a dual core AMD Athlon 64 bit machine which Dell does not make. (They do have dual core Intel though I'm more impressed by AMD's architecture in this area)
I'm willing to bet the FORTRAN compiler used for those programs is not multithreaded so you wouldn't necessarily benefit from a dual core machine. (OK, yes, you can run your virus detection at the same time you run your spreadsheet! Gotta love those marketing people selling those dual cores!)
Thus, I suggest a Dell Dimension E510 for about $700 (Includes flat panel monitor). I would upgrade to 512MB of RAM or more if you use the integrated graphics. If you want to do some casual gaming, I would suggest getting the ATI video card for $50. And if you intend to download PJ-Comix's DUmmie FUnnies PodCasts, you may need more hard drive space!