I have SDL Trados 2006 and installed for the first time 18.104.22.1687.
I take it you're referring to MultiTerm, right?
The customer send me a lot of glossary files with the above extensions. How can I get them into MT?
MTW is the old file format used with MultiTerm 5.x (.mta and .mdf are associated index files). Use MultiTerm Convert to convert them into MT6.x/7.x-compliant XML format.
The conversion process yields two files:
.xdt - use this database definition to create your termbase
.xml - import this file into your newly-created termbase