Can you back that up with a good reason? I mean, other than, "it was a hard class" or "my professor didn't speak english."
I have one W. I dropped out of general chemistry the first quarter of my freshman year because I was taking WAY too many units. I came from a "small suburban city" where it wasn't hard to get straight A's and I thought I could handle 20 units of coursework during my first quarter. Yes, Ego left to make room for Doubt and Insecurity. But, I digress.
So the answer to your question? I think it all depends. If you have >2 Ws, you should probably start thinking of a really good explanation. Especially if they're in science classes. But no, one W hasn't hurt me....yet....