Thanks Jason and Mary Anne for your responses. I guess the crux of my decision will be based on whether the 17-55 will be a significant improvement on my 17-85? If it is only going to be a marginal improvement I should probably keep the kit lens and get the 70-200.
To date my DSLR photography has been mostly of family occasions mostly portrait style. I'd love to do some more landscape and Architecture photography (photography of my work as I am a builder), but I'd also like to be doing more candid portrait stuff and wildlife too so the 70-200 would come in handy.
So is the 17-55 that much better than the 17-85, or should I be looking at supplementing the kit lens with the telephoto and something wider?