Wow, how did this old question get resurrected? Anyway, there is something I don't see in any of the other answers, so I'll chime in:

Unlike Calculus, one of the problem I find with the Diff Eq is that there is no canonical syllabus. So unless U of Saskatchewan does have a very fixed syllabus for the course, the first step is to decide what "flavor" of course you want. For instance, I had a look at a few of the Dover books, but they seem weak if you want a more "modern" (i.e. technology-based / more pictures) approach to ODE's. Which BTW might be the right way to go especially for engineers.

I have yet to find a book that fits my needs, not have I managed to completely pin down what the ideal syllabus should be.