sim vs software.. unlock my iPhone 3G — which one is better?

Stealth sim vs software.. unlock my iPhone 3G — which one is better?
How to unlock my iPhone 3G?
Just got an iphone 3g and would like unlock it now. So I can use T-mobile.. Stealth sim vs software? Is it safer to use any kind of Sim (like Turbo Sim) then softwares? Please help me.. Thank you..