On line Broadcasting Noob - Help Required

Hi all,

Firstly I could not decide where this post belonged, Betamaxed I think meets the requirement more than any other so here it goes.

I'm involved in an on line radio show for a Football club (Soccer for my American friends) and we currently use an system supplied by the club to broadcast live, it requires fans to subscribe to listen. The show has really started to get a good following and we are putting on more 'special' events and would like to get a wider audience for these.

For a while now I've wanted to broadcast a decent on line video stream, but I don't know where to start really. I know I can use the likes of Youtube/Ustream to broadcast, but I'm talking from a more technical standpoint. My budget is not astronomical and would have to probably start with one camera (better than nothing). I have a DSLR I can use and I'm a Mac user, macbook and imac available to use. Take it I'll need an external video device to process it all?

If I wanted to start getting fancy with live graphics, is that something easily achieved? Any words of advice or links to good resources would be really appreciated. People here know what they are talking about so I'm hoping there are some here who can help me out.

Thanks in advance