This is a good example for the situation, where someone does not really need to learn the regular expression language, but instead use a simple action.
Actiontype 7: Import tag fields (guess values)
Source format: %TITLE%
Guessing pattern: %TITLE%.%DUMMY%
From:
Gospel&spiritual 1 - Track 03.[128kb 44khz 2'34]
To:
Gospel&spiritual 1 - Track 03
DD.20100816.1822.CEST