Personally, I think a simple as possible GUI and a 32 bit OS will give me and many folks all the tools I(we) need to make the music I want, I hate getting bogged down in a complex front end of some programs when all i want to do is use the tool at hand.
As systems evolve, programmers tend to fill up available space(mem, drives OS features, leave no byte unused) and somethings can bog down.
64 Bit has it's place but I also like to give an OS several dot versions before I jump in the water. Win7 has yet to be released
Like others have mentioned before to me, midi out to a hardware sound module can be a very nice sound.
Just my POV, Wyndham