looks like you copied the app from someone / your previous PC?
follow the instructions there...
Look for the 'Store' menu, click 'Authorize Computer'

there, enter your iTunes Store password.

simple one.
is there a serial number?
On a real iPhone (2G, 3G, 3G[S]) its in Settings > General > About.

when you have the serial number, you go to
www.apple.com/support/oss
and key in the SN.

if it comes up as unknown SN or any other error, congratulations, you have an iPhony!

Yeah, I can confirm Maybank Debit card works... but only for Malaysian iTunes store, obviously.

@Christopher7
can you google? if the google fails, then come and ask here.

@ axenophage you can't go back officially. feel free to jailbreak

Settings > General > Keyboard.
next time, please google first.

@ koochy_rat its like that by design. you can always turn off the 'sync' feature, its just one click.

how is iTunes *or* iOS supposed to know how to sync to 2 computers? when there's a difference, what to do?

@ Cahill why do you need to sync right now? can't you transfer your old iTunes data from the old computer, and sync afterwards ?

if you do sync, you'll lose whatever you sync-ed from your old computer.