PowerBook 12" G4 to iMac 24"

[MacNewbie]

Hi,

I was hoping that I could get some assistance with a small problem I am having.

My current PowerBook G4 is on the fritz and I don't expect it to live much longer. I have been creating bootable backups with SD and am thinking of buying a new iMac 24". The problem is I would be going from Tiger OS to Leopard OS and from a PowerPC to an Intel based Mac.

1) Will my current bootable backup work on a new iMac?

2) Would it be a good idea to upgrade to Leopard on my PowerBook G4 before it dies so I can at least create a backup with the same operating systems?

3) If the answer is no to both my above questions, what is the best way to backup my existing data on my G4 in preparation for a transition to a new iMac?

Thanks again for you help!