I used to sync my ipad on an asus laptop, now I have a Mac mini and want to sync with it. Can I? Can things be transferred from laptop to Mac mini?

I synced my ipad2 with an asus laptop. Now I have a Mac mini that I want to use for syncing and backup. But when I connected my ipad to the Mac mini it said something about the ipad being already synced to another computer and backup is permitted only one computer at a time. How can I transfer my backup to the Mac mini ? And delete my previous (I.e. asus laptop) iTunes backup system?