Thanks for the quick response, and that's certainly good news for me. After searching the forums, I found that you two (Oscar and Makanyane) have been involved in more than one discussion on this topic (thanks for being patient with the newbie. )

So, if I am correct, I could (using the 30 day 3ds Max trial) import all of the models I needed into 3ds Max and save them all to .max files. I should then be able to open them up in gmax, edit them and then either send them to someone or load the 30 day trial on another computer and export them back to .cas format. Would this work?

@ Oscar Reeve
Thanks alot for the offer, I'll definetely take you up on that offer. Expect an e-mail soon when I finish my first model.

i have gmax as well so if u just save the file as gmax then i could do all the rest if u want ( would only take a couple of minutes )
...
i have managed to do quite a few units that were on gmax and then put them on to 3ds max .
Am I to assume then, that texture wrapping and animations (and whatever else R:TW models require) is imported porperly to gmax from a .max file and is editable without 3ds Max?

Thanks again for the help, this looks like such an amazing community and I can't wait to start modding.