If I unlock my iPhone 4 (AT&T) can I switch it to virgin moble?

The title says it all

Yes. If you unlock your iPhone, you can now use it with any network. Your Virgin Mobile will work flawlessly in your phone, once it's unlocked of course.

Ya sure if you unlock your iphone 4 from AT&T network lock you can freely use it with virgin or any other GSM sim… If you want to unlock your iphone 4 then have a look at sites like http://www.prounlocking.com/apple-iphone-4/rs1wp9/ here they will unlock your iphone using remote unlocking service for affordable cost…