Canon 18-55 II vs Sigma 18-50 2.8-4.5

I've been saving up $100 from each paycheck and by the next one I get I'll have $350 saved up and I want to put it towards more lenses.

$150 will go towards a 50mm 1.8 +taxes/shipping

So I'll have $200 left I can either go with a Canon 18-55 II IS f3.5-5.6

or a Sigma 18-55 f2.8-4.5 OS HSM

I want a wide angle zoom to do landscape type photography so I don't think I'll need a fast lens, but I'm not sure. Is there a type where a fast 18mm is needed? I shoot everything I can from street to bands to macro, etc... I like to try everything. Not a pro at all I just take pictures for my own personal enjoyment.

My current lenses are a EF 35-80 4.5-5.6(which I love)
and a 50mm 1.7 manual focus M42 type, excellent lens but the manual focus kills it's practically.

camera is a 10D which I only like to shoot at 100-800 ISO, it's iffy at 1600/3200 so a fast lens would come in handy with that regard.

A huge plus in the Sigma is that it will be a EF mount instead of EF-S so there will be no modifying necessary to make it fit on my 10D(which i'll be upgrading to a T2i soon)

I have one of the Sigma's you mention and found it to be a very good lens. Not as good as the 15-85 that I upgraded to recently but passes pretty darn good images to the sensor of my 40D. Good enough that the first time I tested a 15-85 in a store I couldn't see any justifiable difference for the money. I'd definitely get the Sigma over the 18-55 IS II. It's still my go to option if I'm going somewhere I might be worried about getting knocked or damaged.

Only big negative is its poor control of flare

Thanks! I was just doing some more reading and it has internal focusing and internal zoom apparently so those two are huge bonuses.

I think I can handle the flare, my 50mm is pretty bad at it also but It's easy to clean up in post. I have CS4 and LR3.5

Yeah, internal focussing and zoom. Non-rotating front element. From an ergonomics perspective, the only issue is the focussing ring moving as the quasi-HSM motor runs.