this might work:
This is how you unpack an sga:
1. Drop the .sga into your coh directory.
2. Open the command prompt (go to Start -> Run -> type "cmd" -> hit enter)
3. Navigate to your coh directory by typing "cd c:\program files\thq\company of heroes" (or wherever your CoH directory is)
4. Once in the directory, type "archive.exe -a [name of the sga].sga -e c:\temp\coh" (or any other directory) This unpacks the sga to the directory specified after "-e"
5. Viola, now you have the contents of the sga.
Troubleshooting: If it doesn't work, check the file name, it has to match exactly.