I wouldn't use T-Mobile, price isn't everything, coverage is way way way more important. You can check coverage maps online, every network has different areas that are covered, as a rule of thumb, Orange and 3 tend to have the best 3G coverage, but Vodafone isn't bad as well. Sometimes, including where i live, i find i dont have a mobile phone signal at all, or even 3G on my mobile phone, but my 3G dongle gets a full 7.2MBPS connection!!! Its pretty random, but nevermind 🙂