I'd suggest you wait until just before you come to Canada, and then choose a network. Both Bell and Telus turned on their HSPA networks this past week (Wednesday & Thursday, respectively), so there is a chance you'll be able to do prepaid on one of their networks in the near future. In fact, I'd be very surprised if it's not available in Vancouver soon, in preparation for the 2010 Winter Olympics. The visiting tourists will expect a real mobile network, not the junk that Canadians have had to put up with for many years.