To simonqu,
You're right that you can apply Ph.D if you hold Master of CS if any professor would accept you.I don't know which university you are studying.McGill University may accept Ph.D student in two years.
to switch from cs to bioinfo, u will need some basic knowledge in biology(don't worry, not that much).
Algorithme and statistic computing is most important in this area, and even a solid basic in mathematics, database will be an important tool in the research, so some knowledge in data mining and data warehouse will be helpful....
If u r pretty sure u like bioinfo and will work for that later, go to biochemistry dept., u can get some lab experience there which will be extremely useful for ur high level study, otherwise cs background will give u a more open future......
Beans:
My problem:
one prof in department of biochemistry in UdeM has conditionally accepted me. but I must apply myself. I don`t know French. so have some problem for application. need you help