According to
http://uk.samsungmobile.com/wcms/pro...K-SGH-D500.jsp
the 3 bands are 900, 1800 and 1900 MHz. 900 and 1800 are used here, and 850 and 1900 there*.
You're therefore looking for a 1900MHz provider in Canada.
http://www.gsmworld.com/roaming/gsminfo/cou_ca.shtml
suggests 3, with coverage maps for two of them.
According to:
http://en.wikipedia.org/wiki/GSM_frequency_ranges
"In Canada, GSM-1900 is the primary frequency used in urban areas with 850 as a backup, and GSM-850 being the primary rural frequency."
It will depend on where you're going - if it's a city try and get detailed coverage maps from one of the GSM providers mentioned in the link above. If it's somewhere like rural Quebec, then you may be better off with a whistle (and learning French!).
Obviously, talk to your SIM provider to make sure that it can roam there.
*it gets a bit more complicated elsewhere in the world.