will u need broadband to download the extra stuff for xbox360

Not as far as I know, why they would do that I don't know, but you need High-speed internet just to access X-box Live so broad-band internet would be helpful .

are highspeed and broadband not the same thing? also i think i heard maybe that you will no longer need high speed for xbox live as they are implementing a new xbox live for the x360.

High-speed and Broad-band are not the same thing, Broad-band is just a type of internet you can get, and one of the ones required for X-Box live.

Why you could download a mods onto the 360 on a 56K modem but not the X-Box is completly beyond me, thats like backwards compatiblityx1000. It just makes no sence, seeing as 56K modems have almost gone the way of the Dodo.

Well I'm not sure about this stuff, but I play halo 2 on Xbox Live, downloaded those maps and stuff and I use DSL (router box) which works fine. Faster internet might reduce the download time but unless your for online play, I doubt you need fast internet.