HTC HD2 or desire from Telstra

[junkie]

as the title states, looking at getting a HD2 (or the Desire if it lands in april as announced) from telstra to use on Telus' HSPA network. not worried about voice, as it supports all the bands, but for data it will only support the 850MHz band.

Question is how much will that affect my ability to receive 3g speeds on the handset being limited to 850, and not having 1900 in there too? I'm fairly sure I'll be ok in the city (Calgary) but what about traveling in alberta is there a way to check and see which telus towers have 850/1900 transmitters, or just 850, just 1900?

thanks,