there are a lot of places to ride in the netherlands. Probably the best is riversidewakeboarding.nl in Arnheim about 60 miles a way. They're really nice and have a malibu VLX.
If You want something closer there's a cable park im Almere (http://lido-almere.nl/?t=skibaan&p=wakeboard
) about 18 miles away.
An ther is the wakeboardschoolamsterdam.nl, but I don't know them.