hi you you would probably get a faster/better/more response over on the canon forum.
But here goes:
The sigam 18-50 is not HSM for canon only nikon so it can be used on the low end cams D50 etc that dont have a motor in the body (I know canon does not have a motor in the body as EOS never has). It uses a micro motor which will be slower and noisier the HSM but no less capable. as a lens its quite a good one to go for, you could also look at the Tamron 17-50 2.8 which gets a very loyal following. also the Sigma 17-70 2.8-4 is not too bad if you want a bit more lenght.
The 17-85 IS usm is not the best opticaly but a fairly good alround snappers lens. It does have IS but is a slower lens to start with.
The 17-55 IS is probably the the best to go for but is very expensive and quite large but opticaly very good indeed.
Have a look at some of the revies for these
as for you other choices they both seem good choices however have a think about the canon 60 macro as its excellent and can be had quite cheap 2nd hand.
also you might want to look at the older versions of the 70-200 sigma as the latest version seems to have a few quality problems which is a shame as the older ones are great. That and the 100-300 f4 are probably some of the best budget quality glass you can get.
The Canon 17-55 IS is stellar. The 17-85 IS is a travel / general purpose lens. The Sigma is a Sigma, you might get a good copy.
If you can afford it the 17-55 IS is worth it, I was very happy with it's optical performance when I had one. It is not built like an $800 lens should be though, it's not built any better than the 17-85 IS.
If you won't be shooting in the low light a lot the 17-85 is very nice and one of my favorite Canon crop lenses. It's strength is its versatility.
Since you don't seem to mind size as your planning on getting a 70-200 f/2.8 I'd get the Canon 17-55 f/2.8 IS no question. That way you have two fast zoom.
