hey i plan on buying the 550D in september and i would like to know if it matters what lens you have on your camera for video or not?  what i mean is, can i use any lens iwant?  can i film with m42 lenses and such?  will there be a difference when i'm filming? 

Tamron's 17-50mm f/2.8 nah try get the sigma version of it if you can affort it
faster focus HSM also OS sigma's VC build is better and sharper from what i heard i stay away tamron lenses looks/feel cheap in my opinion