As Vince wrote, nothing should be in the normal update location that is not meant for everyone. Any beta build, whether to test a fix for a single user's problem or a generic one, should be delivered in the beta directory. A strictly private build should not only not be delivered via the common update path, but it should not even share its version number format with the production versions; all communications relating should be private.
BTW, I now use both 32b and 64b versions on my one Win7 system, and the 32b version on my two XP systems. I report this only for future reference.