I'm in Australia. Originally I planned to switch from Telstra (AT&T frequency) to Optus (T-mobile frequency) when I got my N900 (I call her Betsy and introduce her to everyone as my internet bride).

I'm not a heavy data user and my occasional browsing on the bus was OK on 2.5g so I didn't change carriers.

(Ovi maps is a pain but I haven't used map loader yet.)