Vista - Script - Registry Redirection Issue

I have created a script that writes a few values related to IE in the
registry. When the script is run on Vista x64 some registry values go to the
x64 part and some to x86 part of the registry, e.g.

These registry values go into the x64 part:

HKLM\Software\Policies\Microsoft\Windows\CurrentVersion\Internet
Settings\Security_HKLM_only
HKLM\Software\Policies\Microsoft\Internet Explorer\Control Panel\PrivacyTab

These registry values go into the x86 part:

HKLM\Software\Wow6432Node\Microsoft\Windows\CurrentVersion\Internet
Settings\EnableHttp1_1
HKLM\Software\Wow6432Node\Microsoft\Windows\CurrentVersion\Internet
Settings\Zones\*

Any idea why this is happening? How could the "Security_HKLM_only" registry
value be configured for IE7-32bit? Any suggestion would be greatly
appreciated. Thanks.