Upload SP2007 list templates to SP2010

Solution:

1. Rename the original .STP to .CAB
2. Extract its manifest.xml and other contents (if any) to a local folder (lets call it [folder])
3. Search for the ProductVersion element. This should have a value of 3
4. Change its value to 4
5. Repackage the manifest.xml into a .CAB. I've done this by using makecab.exe in the C:\Windows\System32 folder
   Syntax: makecab.exe [folder]\manifest.xml [folder]\{template-name}.cab
6. Change the generated cabinet's extension from .CAB back to .STP and upload it into the _catalogs/lt

References:

http://www.heyweb.net/2010/09/converting-sharepoint-2007-list-templates-for-sharepoint-2010/

http://tom-dw.blogspot.com/2010/06/importing-sharepoint-2007-list.html