Dear Jurgen,
I had the very same problem when I began regular daily meditation after attending the level 1/2 seminar in early December. My monkey mind was all over the place.
I've been amazed at the progress on that end, so for now give yourself a break and know that quietness will come with time.
The way I handle the stray thoughts, pretty much in keeping with Master Lin's tips in his Born a Healer book, is to do this:
When it's a thought I need but not during the meditation (ie "what shall I make for dinner tonight?"), I say in my mind, "Thank you for coming. Please return when I need you."
When it's a thought I really would prefer never to have again because it's repetitive and counter-productive in my life (ie "oh why can't I lose weight," "the apartment is never clean enough," "oh poor me, when will my headache ever end?"), I say, "Thank you for coming. You have served in my life and now it's time for you to leave me and return to the universe."
I find it remarkable how effective this is. Some I can zap immediately, some take a few more nudges (especially the ingrained ones), but overall I watch the thoughts float away, where I envision them returning to the universe and transforming into something the universe needs, like rain for the tree outside my window.
Hope this helps! Good luck,
Carebear
(fellow newbie student)