I just returned from Quebec, and I now know what CEGEP means. :)
If you look further on my web-site, under UBC stats, you'll discover that the average grades of an accepted applicant are in the range of 80-82%. So, your numbers aren't bad at all. Naturally, you will want to do as well as possible on your MCAT test.
Medical school admissions is a funny thing. Many good applicants don't succeed at one school, but they do at another school. Because of this, it's really impossible for me to give you any solid answers. If it helps, your GPA is within the acceptable range at my school, UBC. I think that 80% is a reasonably solid GPA for applying into most Canadian medical schools.