It seems you had the Measurement Converter Smart Tag. You can download
the Word 2002 version from
http://www.microsoft.com/downloads/details.aspx?FamilyID=F67FC42C-5F41-4C3F-9D5A-71354471DC32
but I can't get it to work with Word 2003.
The 2007 version comes with Office 2007, but you may not have
installed it. In the Control Panel, run Add/Remove Programs, select
Office 2007, and click the Change button. In the tree diagram of
features, Smart Tag Plugins are listed under Office Tools. Make sure
the ones you want are set to "Run from my computer" and click Update.
That said, I haven't been able to get Word 2007 to recognize that the
measurement converter is installed. It doesn't even appear in the list
of tags that are available but turned off. (To see and change that
list, click Office button > Word Options > Add-ins, set the Manage
dropdown to "Smart Tags", and click the Go button.)