It's a rather convoluted thing though, Nikon's lens history. Certain modern bodies will work with most older lenses however lower end modern bodies will lack certain features and may not be compatible, in fact damage due to mounting is possible. Similarly Nikon's T/S lenses may not work on all modern or older bodies either.
The 14-24 is an unusual and stellar lens. Likely outperforming many Nikon wide primes as well from what I've seen. The 16-35 and 17-40 from Canon are very good as well, and price wise (always a factor) are very competitive with anyone else. The 10-22 is an amazing lens for the money, too bad I cannot use it on my main camera. Like you the 17-40 is my lens of choice at the wide end, I do not need the speed generally and the size and weight savings means I can carry that much more other crap.
I'm not sure I'd say the 14-24, Nikon's defocus controls, Canon's T/S or any of the other lenses are strong arguments for either system in most senses. If you need them you're essentially an outlier in the photographic world, a unique case, and of course you will acquire the equipment you need and it may dictate the system you choose. I for example have been shooting Canon for a long time and up until a few years ago lens-wise it wouldn't have mattered what I used. However the Canon 24-105 4L IS and 17-40 4L are perfect lenses for my needs, I don't need or want their faster counterparts. The IS on the 24-105 allows handholding at lower speeds at the apertures I use which are generally not wide open but two stops down ore more, the 2.8L would be a worse lens for me. Nikon for instance has nothing that really can match the two of those lenses, and yes i know about their 24-120 VR.
It wasn't until a little over a year ago that I bought the 24 TS-E and 90 TS-E that I really had something that Nikon couldn't even approximate let alone match. Now they do have equivalents but I don't feel personally the very large price increase is worth it for theirs anyway so I'm quite happy with what I've got.
Nikon has regained most of that ground. They are very competitive with Canon on the super-teles but as with every other part of the focal length range each one has the upper hand in certain cases in performance, as well as cost.
For what it's worth many of Nikon's kit lenses are generally a bit more expensive than Canon's and while sometimes technically better, they're still not terribly good. However for most people if they're sticking with the kit lenses they're likely going to be the kind of shooter that's fine with either.
That would be a good way to start however you'd also have the Rebel XSi, an older XTi or the 30D or 40D to consider on the Canon side with similar lenses. Ultimately your best way to decide is to try them all out. Just like shoes or cars, cameras from different manufacturers (or even models from the same manufacturer) work, fit and feel differently.
Ergonomically the Rebel series and the lower end Nikons are both compromises. They both have small and dim viewfinders and both have focusing screens that make determining real depth of field very difficult if not nearly impossible. The XSi is a brigther viewfinder but like the other lower end Nikons and Canons it's still on the smaller side. Still for a casual shooter that may not always be something that concerns them.
Controls, layout, size and overall fit and finish of the lower end cameras are not as good as the higher end. The Nikon D60 may feel a bit tougher but it isn't any tougher than the XSi and feature wise they differ some so look at features if they matter, however more important in most cases is whether the camera works for you and whether you have specific needs for certain optics.
Pentax beats Canon and Nikon on lower model build quality and ergonomics IMO but falls behind on the features. Very nice cameras regardless.
Regarding fast lenses to choose from. The Canon 50 1.4 is a fine lens, better than the older Nikon 50 1.4 but certainly probably bested by the new one but I haven't used the new Nikon 50 1.4 (or the new Sigma 50 1.4). The Canon 50 1.8 is an amazing deal and a very solid performer for all of $80 or $90 so if you want something fast on a budget consider it. I'll second the 85 1.8 suggestion and I hear the 100 f/2 is very good but I've never used it. I've got the f2.8 USM macro myself.
So my suggestion as always to someone looking at jumping in to a new system with cold feet is to go to a store that has a variety to choose from and try everything in your budget out. Never just take one person's advice to buy from camera x or brand y, decide for yourself because one camera might fit your hands better or you'll like the interface better. If you do it right you'll have a system you'll be happy to grow in to and grow with, if you do it wrong and you get in to it you may find yourself losing money in a change to another system. Major players in the DSLR business are Canon, Nikon, Pentax, Sony and trailing somewhere behind with the 4/3 system is Olympus. Personally the 4/3 system is not worth it generally but if it feels right don't run away from it.
If I weren't getting Canon or Nikon I'd go with Pentax. That's just me though.