Microsoft will be releasing IE9 on March 14th: http://windowsteamblog.com/ie/b/ie/archive/2011/03/09/a-more-beautiful-web-launches-on-march-14th.aspx
The RTM version is likely to have some bugs that will break LDLS 3.0g; to prevent the conflict, see http://community.logos.com/forums/t/30926.aspx.
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Microsoft will be distributing IE9 via Windows Update; if you want to prevent it being installed automatically, you can open/create the "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Setup\9.0" registry key, then create a DWORD value named "DoNotAllowIE90" with the value 1.
We have provided a .reg file that can set this value automatically: http://www.logos.com/media/update/BlockIE9.zip