hmm - eclipse should not be requiring that much memory that you need a 64bit memory space to let it run!!
If your eclipse is using more than 2 GB of memory there is something very wrong. Heck, even more than 1 GB is bad.
About 64 bit edition, then the visual editor depends on xulrununer which unfortunately is not available in a stable 64 bit version.
We have thus made it so you can run 99% of JBooss Tools with 64 bit but when you use the visual page editor it will show an error;
anything else should just work.