Windows 32bit Family XP RTM - 5.1.2600
XP SP1a - 1106
XP SP2 - 2180
Server 2003 RTM - 5.2.3790
Server 2003 SP1 - 1830
Server 2003 SP2 - 3959
Vista RTM - 6000.16386
Server 2008 Beta 3 - 6001.16510
Windows 64bit Family XP 64bit RTM - 5.2.3790.1830
XP 64bit SP2 - 3959
Server 2003 64bit RTM - 5.2.3790.1830
Server 2003 64bit SP2 - 3959
Vista 64bit RTM - 6000.16386
Server 2008 64bit Beta 3 - 6001.16510
What this means is that the forthcoming Firefox 3 release will break some Silverlight 1.0 installation experiences on web sites that used the original Silverlight 1.0 SDK Silverlight.js detection file.
The Silverlight 2 SDK has an updated Silverlight.js file that not only solves this problem for all versions of Silverlight but also eliminates browser restart that was previously needed for new installs.