HehHeh, yep you should get cracking
Start with 2.41 if thats all you can get going at the moment, does the source not have a config and make script? If so the config script should tell you all about its options, in particular look for SSE optomizations and the like. Or you could run a 32 bit build of 2.42
Blender is capable of a fair amount, the one thing holding it back from being used in my work instead of my hobby is the lack of in program translations of scale. Meaning being able to set the scale to feet and inches, or meters, or anything other than the arbitrary BU. Dont get me wrong I have and will continue to translate the BU when I need to, just those in program scale translations would help me a LOT, as well as some basic snaps(Line,Endpoint, Midpoint, Perpindicular, Continuations, etc) I am not trying to turn blender into a full blown CAM program, but the basic CAD functionality I would love, until then if I do any more scenic designs it is back to AutoCad or Vectorworks unfortunatly.
Blender's UI will take you a LOT of getting used to probably, but it is extremely fast, I havent used one faster yet, when you do. One hand on the keyboard, and one on the mouse, learn to love it.
At any rate 2.41 should hold you over till you get into the advanaced stuff that is beyond my abilities at the moment, fluid simulations I am working on but IPOs I still need to learn etc, and I only do basic animations at the moment.