Lens family selections for Canon

[leebase]

I've decided on a digital camera body -- the Canon EOS 300D (Digital Rebel)

I have no existing Canon lenses. They have a basic consumer lens for $100 in the camera kit but I think I'm going to skip that.

My desire is to begin to work toward a set of lenses for the occasional professional gig. In addition I want to take sports shots of my kids, but I don't have the same "professional" need there.

I want to be able to get low light shots (as in a Church).

I'm thinking of 3 lenses. A professional grade wide zoom, a professional grade prime and a consomer grade tele-zoom. I'd like advice on specific lense options as well as on my overall "theory".

For the wide tele -- I'm considering the following 2 choices:

Canon 24-70 F/2.8 L $1350
Sigma 24-70 F/2.8 EX DF $400

Obviously there is a big price difference, but the same speed and range. Not sure what I'd be compromising by selecting the Sigma. As I'm shooting with a 1.6 crop digital camera, I stuck with the 24mm wide options and did not consider lenses starting at 28. Should I reconsider?

For the prime:

Canon 50mm F/1.8 $80

I'm assuming this can be used for portraits as well as "party shots". Should I consider a 35mm prime instead?

I'm really stuck on the tele zoom. I'm not even sure what my parameters should be. I'm not looking for an "evening" lens at this point. Just something that can shoot good shots of kids playing soccer or softball etc. Something shot most of the time hand held. Somthing that is not terribly expensive of heavy.

Obviously I'm not looking for a pro lens in this category at this time.

TIA,

Lee