I have an itunes account and have gotten a bunch of iphone apps. I use these for my old ipod touch. I will probably get the iphone 4 soon and don't know if that will require me to get a new itunes account. If I have to get a new itunes account, then will I be able to use my old apps? My wife will probably get an iphone as well. I live in Japan so the system might be different than in the U.S.