Which lens with what DSLR?

I'm looking to buy the Nikon D3100 or the Canon 550D (aka Canon EOS Rebel T2i)
I'm mainly going to shoot bmx and what the camera defiantly for its video aspects too so could you help out choosing one with a lens Kit.

Was looking on buying the Nikon D3100 with the 18-55mm and the 55-200mm lens
[ Nikon D3100 14.2MP Digital SLR Camera with 18-55mm f/3.5-5.6 AF-S DX VR Nikkor Zoom Lens and the Nikon 55-200mm f/4-5.6G ED IF AF-S DX VR [Vibration Reduction] Nikkor Zoom Lens ]
Or should I rather buy the body with a 18-200mm lens (someone once mentioned it and haven't got an example of one)

And with the Canon 550D the 18-55mm and the 55-250mm lens
[Canon EOS Rebel T2i 18 MP CMOS APS-C Digital SLR Camera with 3.0-Inch LCD and EF-S 18-55mm f/3.5-5.6 IS Lens and the Canon EF-S 55-250mm f/4.0-5.6 IS Telephoto Zoom Lens for Canon Digital SLR Cameras]
The same with the Canon should I rather buy only the body and then the 18-200mm

Please give me your choice of kit and if you prefer different lenses please mention them.

And what's your choice of Camera bag (must be a backpack) it should have save place to store the camera with 2 lenses and a flash (that's when i get more money to buy a flash). Would like to store my bmx helmet in there for if we go riding that I can have my camera and the helmet for if I want to ride to. Was looking at the [LowePro Flipside 200 Backpack] or the [LowePro Fastpack 100]. Please help out because this is something i would really like to have (A bag that can support both of my needs and not two bags)

Your advice would be appreciated.

**BTW it's my first DSLR and can't wait to start taking photos on a DSLR**

Most of the less expensive DSLRs such as the Nikon D3100 are sold with the 'kit' lens, usually a 18 to 55mm. Some are sold as a twin lens kit with 18 to 55 and 55 to 200 or similar, so you might find it hard to buy a D3100 as 'body only' and then buy perhaps a 18 to 200. Basicaly you are wanting to cover most options from medium wide-angle (18mm) to fairly long tele (200mm or more). Partly it will depend on the offers available from various sources as to which you buy; both Nikon and Canon are good brands.