Love Fish: Once again, without seeing the switch, I can't really tell you; all I can say is 90% of the time, switches go in-line with the negative lead - meaning, cut the wire, one end goes into the switch, the other end comes out.
Also, from your drawing, you have 2 bulbs connected with two positive leads, and 2 with negative leads. I'm not sure if that's what you itend to do or not, but it won't work; each bulb needs one positive and one negative lead.