Can I transfer all my data when I upgrade to the iPhone 5?

Data as in "SONGS" apps photos contacts ect.

Added (1). I currently have a iphone 4

Yes, you can if you have iCloud set up on your other iPhone when you enter your apple id it should transfer automatically

If you already have an iPhone just back it up first, by plugging it into your computer and letting it sync with iTunes.

Then plug your new iPhone 5 into your computer. As you go through the step-by-step registration process you will be asked if you would like to restore from the latest backup. Just select Yes and all of your data including songs, contacts, diary etc. Will be copied to your new iPhone.

All of your Wi-Fi settings will be deleted so you will just have to add these.

You can back up your data using iTunes or iCloud. Make sure you select everything while backing up. You can restore it on your new IPhone 5. Enjoy iPhone 5

Yeah as far as I know with icloud… I haven't been an apple user long, but I'm pretty sure thats what icloud can be used for… If not you can always just transfer the files onto a computer then onto your new phone…

Stuff that will transfer automatically -
Contacts
Photos in your iCloud account
Calendars
Apps and media purchased through iTunes that's still available on iTunes

Stuff that you'll have to sync from your computer -
Photos not in your iCloud account
iOS apps that are stored on your computer but no longer available on the iOS App Store
Media stored on your computer that you obtained from sources other than iTunes
Media stored on your computer that you obtained from iTunes but is no longer available through in the iTunes Music Store

iTunes Match audio streaming will also be available when you associate your new iPhone with your iCloud account.