the 18-55mm is a good start...  you could go for a second hand 17-85mm Canon - it is a very good "standard" walkabout lens and has IS (image stabalisation) so you can use it nicely indoors as well.

As for sigma - i dont have much experience with the "kit"-type lens you are thinking of as i went the canon route with that.  (kit 18-55 then upgraded to the 17-85)

Urm - www.fredmiranda.com - try that for lens reviews... have a look at the sigma and canon ranges and there is tamron in there i think too which also worth a look.  Basically you wont be disappointed majorly, as upgrading to a dslr over a compact is a big leap in itself... it is only when you get very perfectionist with image quality that you realise "oh maybe i shouldnt have gone for the cheap lens"  But the thing is, if you are buying second hand, you dont really loose too much money reselling i think.  Other people will probably kill me for saying this but i think the kit lens (18-55) for the canon is a good idea - you can get it for about £50 on eBay as far as i remember... my copy was fine and i was impressed with the quality for the price (which is what you really ahve to think about, not compare it to another lens of the same focal length as it wont win, i'm willing to conceed that... but the "other lens" is at least double the price in most instances).  What is your budget anyway?  I might be able to suggest some options if i knew that...

Oh and welcome back to the world of onlineness ;) 

"In every colour, there's the light.
In every stone sleeps a crystal.
Remember the Shaman, when he used to say:
Man is the dream of the Dolphin"

Rich Meadows Photography