I recently completed my BSc in honours computer science (with a minor in maths) at McGill, and since Montreal and McGill are such fun, I decided that I'd stay here for my MSc, which I'm currently working on. I'm originally from Finland, but grew up in Germany, and before arriving in Canada, I wasn't at all sure what I should be studying at university.
In high school, I always thought I'd end up studying maths or maybe physics, and I agonised for quite some time over courses in my first term. Flipping through the yellow pages at the back of the undergraduate programs calendar (now all online), I discovered that many of the descriptions of the courses in the computer science department sounded very intriguing. On a bit of a whim, I registered for some of them. By my third term or so, I was taking only maths and computer science courses, and I never regretted the decision.
I'm now working on some issues in proof theory and automated theorem proving in different logics. Proof theory is the study of proofs as rigorously formalised mathematical objects, while automated theorem proving is the study of how we can automate the task of constructing such proofs. It's a wonderful mix of theory and application, and also great fun, believe me. In my treasured spare time, I enjoy fine cinema, Tetris, Wikipedia, and long walks around the city.
The CS department at McGill offers a lot of very diverse courses, and it's worth it to try anything and everything that sounds engaging. You might become interested in things that you'd never thought about before. I'm still getting used to being a graduate student, but there's no question that my McGill undergraduate degree has provided me with a great foundation for my current (and future) studies.