how can I transfer empty space between partitions?
I haven’t tried any way of resizing the partitions through Disk Utility, but that doesn’t mean it’s impossible. (Before I go on, consider this the ever-important reminder that when fiddling with disk partitions and stuff, have a good backup. And then some. And then another one).

So here are my two suggestions:


You could try backing up the Snow Leopard partition to two external drives (one for backup, one for the copy). Then delete the original partition, and put in a new one to fill the space. Finally, restore the copy back onto the new (larger) partition
iPartition from Coriolis Software sounds like it would be able to do what you’re doing. I haven’t used iPartition, but I have used their other product, iDefrag, and that worked fine for what I needed. It costs $46.95, but there’s a free demo that you can try. Not sure what the limitations are, but this seems like the safest option.