Hi Al, unfortunately there's a considerable amount of work involved in producing a 64-bit version so it's not likely to happen anytime soon.

In the meantime there are some settings you can adjust to reduce memory consumption on heavy files, see this previous post for some details:
http://moi3d.com/forum/index.php?webtag=MOI&msg=5322.2

If you adjust the display settings as mentioned there ("Mesh angle" with a rougher value like 25 degrees and uncheck "Add detail to inflections"), that will make a coarser display mesh and use less memory for the loaded file. The default display settings are more tuned for a high quality display but that also makes for excess memory consumption when high detailed models are involved.

- Michael