I can understand that it if your development environment doesn't allow for it, that you can't do a 64-bit version.
As someone who is keenly awaiting Windows 7 (I actually bought a new powerful 64-bit capable PC!) and am now using Vista 64-bit, I thought that it would be preferable for all my programs to be 64-bit? Maybe it doesn't make a difference but I've been in this PC game a long time and have seen all sorts of issues over the years with "compatibility modes" on NT, OS/2, etc.