I have a Canon Digital Rebel Xti 10.1 Mpixel camera with the standard 18-55mm lens. I want to buy a Tiffen lens kit. I thought I should buy a 55mm lens kit; however, I purchased this camera through NewEgg; they try to get you to purchase a lens kit with the camera. The only thing is, they are offering up a 77mm lens kit. So, now I'm confused. What gives?

The 18-55mm kit lens takes a 58 mm filter.
http://photo.net/equipment/canon/efs18-55/