I think the number estimated between 20.000 to 25.000 all together. Including certain... less-then-useful units. Most Dutch Waffen-SS'ers joined out of anti-communism. Or boredom. I've read some newspapers from the war. These people really were bombarded with propaganda and joining up didn't seem too bad. A well-paid job, too. But yeah, they made their choice, for whatever reason. Saying that they all were true Nazi's is as stupid as saying that they all weren't.
A little word of advice guys - When you visit the Netherlands, it's best to not mention all those Dutchmen that joined the Nazi's. It's a bit of a ....sensitive subject. There are plenty of people who know why those men made their choices, but for everyone one of those, you got 10 right-wingers saying they only fight to fight communism and that the Nazi's weren't all that bad and a hundred ignorant Dutchies saying 'THEY ALL BE NAZI JEWKILLING TRAITOR SCUM'.
Like I said...Sensitive subject.