in the resisgry for NT

HKEY_USERS
.DEFAULT
########

where #### indicate a unique ID for logged in users.

two questions:

1) how can I get a list of what's under HKEY_USERS?
I've been able to enumerate KEYS that are below (for example) .DEFAULT but not just HKEY_USERS

2) How can I determine which "#" is for the current user?

-josh