Vista: registry access from BHO

[Alex Mizrahi]

(probably a bit offtopic here, but i haven't found a better place..)

i'm developing IE extension that is a BHO (plus some button handlers).
this extension can be enabled/disable on per-user basis -- installer writes
registry entry to HKCU\Software\.. to indicate it's enabled, and
additionally it can be enabled for all users via HKLM entry.

this works fine on Windows XP, however for Vista it has a problem: on Vista
registry is "virtualized" for security reasons. access to
HKCU\Software\myplugin goes into

HKCU\Software\Microsoft\Internet
Explorer\InternetRegistry\USER\{SID}\Software\myplugin

what's interesting both read and write access is redirected, so i can't see
from plugin if it's enabled by installer.

any ideas how to do this?

registry path has dynamic {SID} in it, so it would be tricky to do this in
installer.. (i'm using dumb one from MSVS so far)
i've read something about Software\LowRegistry that should be accessible in
theory, but it gets redirected too..

also an interesting effect, it seems _sometimes_ there's some connection
between isolated registry and normal -- they see each other. however i was
unable to reproduce this behaviour in stable way, so it could be just my
imagination..