jailbreaking an iphone with a different itunes account
I am wanting to jailbrake my iphone 4, butI don't have a computer with itunes on it. I have a friend who knows how to jailbrake and she has itunes and the jailbrake apps on her computer. If I have her jailbrake it without sinking with iTunes or by loging into my account, will I lose all my contacts? I know I'll lose all my music and apps but I can just redownload them all again later. However I can't with contacts because there aren't stored anywhere on my phone and I can't get iTunes on my computer I have because it has an administrator password. So, if anyone knows a way I can jailbrake without losing contacts and other things such as calindar events, please let me know.
Thanks so much,