I *felt* nervous on slicks, but then had a couple of "just gotta ride through that!" including one that was a turn through gravel... the tires were fine. It was my head that was the trouble. That might not be true for you -- and, of course, there are semi-knobby options. How skinny are the tyres?
My Dutch Commuting bike has some really sweet wide tires that have knobs on the outside but not in the middle. It works really well.