Someone else asked this same question about a week ago. I'll post exactly what I posted in that thread
I had about 14 W's on my transcripts. Some of them were from over 15 years ago when I thought I dropped out of a semester but didn't so got F's in them. The college made them retroactive W's since I actually still had the drop form signed by the professors. About 6 W's were from the CC I went to part time and were spread over a 4 year period. 3 of them were from one semester when I had surgery mid-way through the semester and withdrew from school. The other 3 were just from classes I was doing crappy in from lack of effort. I wasn't asked about any of them at any interviews. I'm not sure on the exact number of W's, I would have to look, but it was a lot and this gives you an idea of how devastating your 1 W will be.
Good luck!
Edit--I forgot the two W's that I had at the University I got my BA from. I had two, one in pathobiology, and one in gen. chem I. I of course retook Chem. I and did fine in it (A-) even with it being a requirement for medical school, I wasn't asked about it. To summarize: I certainly wouldn't worry too much about a few W's.