64 Bit..when?

So, 64 bit versions of windows have been around for ages now, when will the right time come to change from 32 - 64.

As far as i know OS X is 64 (let me know if im wrong). is there much of a benefit from 32-64 at the moment, and is there potential performance for 64 if more widely adopted?

Basically i just dont get why we have have had it so long and it hasnt been snatched up.

well... last weekend my Windows 32 installation finally stop working properly (tried rebuilding 3 CD's and switch 3 optical drives and it still freeze before the blue screen of prompt) so I switch to 64 which oddly boots properly. Now that I find out they don't support validation for the 64bit windows XP (probably have that in Vista, but oh well), all the nice things (except minor glitches in games)

so I am saying as long as the 32-bit version still works people will be reluctant to switch (Gees, my game loadup time is long in my x64 XP) and unless there is incentive of needing more than 2GB (x86 XP the max memopry an app can allocate is 2GB IIRC) of RAM there will be resistance