Replying to Lens Help

Ok so I'm thinking about purchasing a Canon Rebel XTI. I've been looking around for a little. This will be my first DSLR so I need some help. There is a package with a Tamron 28-80mm with a 1gb card,case,tripod,cleaning kit for $537. Then there is another kit for $50 more. That kit comes with Canon 18-55mm lens and 4gb card and the same accessories as the other kit. First of all which is a better lens? Then is this even a good deal. I've looking around and it seem pretty good but do you think I could find a better deal? Thanks guys.