I doubt if there's a program to unencrypt a Windows Mobile encrypted file on a PC.
In that case, the solution would be to open the file on your phone (which still can) and save it as an unencrypted doc. Then move that to where-ever you want. It's some work, if it are a lot of files, but if the content is important enought it might be worth the trouble.
Our general recommendation is to have an unencrypted backup copy of encrypted files stored in a safe place, just to cover circumstances like this.