Just wondering why you would want a 64 bit kernel? ZS never uses anywhere near 4 GB of RAM. As a matter of fact on my systems (which I am on the 3d now) it never used more than 128 MB of RAM, ever. Right now it is using 100 MB after almost 1 year uptime. A 64 bit kernel would be requried if you ran memory hungry applications which needed more than 4 GB each. Otherwise it would just bloat your memory allocation with no tangible gain.