For more technical details about the Mshtml.dll Update, see Microsoft Knowledge Base (KB) article Q250.

Whose Computer Is at Risk?
Here is a list of operating systems and updates for the English language version only. (International language versions also may be available.)

Windows 98
Internet Explorer 5.01 and Internet Tools		Update not needed.
Internet Explorer 5 and Internet Tools		Update not needed.
Internet Explorer 4.01 Service Pack 2		Your computer needs the update. Click here to download.
Internet Explorer 4.01 Service Pack 1		Your computer needs the update. Click here to download.
Internet Explorer 4.01		You need to upgrade to Internet Explorer 4.01 Service Pack 2 by clicking here. Then, return to this site and click here to download the fix. NOTE: Upgrading to Internet Explorer 5.01 will eliminate the need to download this update.
Windows 95
Internet Explorer 5.01 and Internet Tools		Update not needed.
Internet Explorer 5 and Internet Tools		Update not needed.
Internet Explorer 4.01 Service Pack 2		Your computer needs the update. Click here to download.
Internet Explorer 4.01 Service Pack 1		Your computer needs the update. Click here to download.
Internet Explorer 4.01		You need to upgrade to Internet Explorer 4.01 Service Pack 2 by clicking here. Then, return to this site and click here to download the update. NOTE: Upgrading to Internet Explorer 5.01 will eliminate the need to download this update.
Windows NT 4.0 (x86)
Internet Explorer 5.01 and Internet Tools		Update not needed.
Internet Explorer 5 and Internet Tools		Update not needed.
Internet Explorer 4.01 Service Pack 2		Your computer needs the update. Click here to download.
Internet Explorer 4.01 Service Pack 1		Your computer needs the update. Click here to download.
Internet Explorer 4.01		You need to upgrade to Internet Explorer 4.01 Service Pack 2 by clicking here. Then, return to this site and click here to download the update. NOTE: Upgrading to Internet Explorer 5.01 will eliminate the need to download this update.
Windows NT 4.0 (DEC Alpha)
Internet Explorer 5 and Internet Tools		Update not needed.
Internet Explorer 4.01 Service Pack 2		Your computer needs the update. Click here to download.
Internet Explorer 4.01 Service Pack 1		Your computer needs the update. Click here to download.
Internet Explorer 4.01		You need to upgrade to Internet Explorer 4.01 Service Pack 2 by clicking here. Then, return to this site and click here to download the update. NOTE: Upgrading to Internet Explorer 5.0 will eliminate the need to download this update.
Windows 3.1 and Windows NT 3.51
Internet Explorer (all versions)		Update not needed.
Macintosh
Internet Explorer (all versions)		Update not needed.
Unix (Solaris)
Internet Explorer (all versions)		Update not needed.
Unix (HP-UX)
Internet Explorer (all versions)		Update not needed.