Switching 3GS and 3G sims....will it work?

[MatrixPrime]

A coworker would like to buy an iPhone, and I told her I would make her a deal, but I need to know if this works or not. I told her I would pay for a new iPhone 3GS, give her my current 3G for free, and then just swap sim cards.

Will this work? Will apps I bought be able to sync to the new phone? Will my phone account have any issues?

 

[exhibit.b]

it will work just fine. no problem at all.