Q: How do I move all files from an old PPC to a new Mac Mini?

What other equipment do you have? External hard drive?

I've seen BabyBoomer recommedn AOL IM or iChat if you have a fast network connection.

How many files (GB)?

I'd take them off the external HD or connect the two Macs by Firewire, boot the PPC into Target Mode and copy them over.

By new you mean a 2011 model Mac Mini running

Lion, first thing to be aware of is that none of the

PPC apps are going to work as Lion no longer supports

the Rosetta PPC emulation.

If you want to try Migration Assistant, check this:

http://support.apple.com/kb/HT4889

How well this will work depends on the OSX version on the PPC.

But, if all you want to do is copy data, you can just connect

the hard drive to the Mini and move what ever you want to

it.

The new mini has a Firewire 800 port. Likely the PPC version only has Firewire 400.  The OP will need a converter cable which is why I was asking first about what hardware is available and how much is being copied.

Probably go with using the external hard drive if you decide all you want are data files.

If you want to migrate:

Kappy: A Basic Guide for Migrating to Intel-Macs - http://discussions.apple.com/message/10257343

Mac OS X 10.3, 10.4: Transferring data with Setup Assistant / Migration Assistant FAQ - http://support.apple.com/kb/HT1554

Setting-up a new Mac from an old one or its Backups - http://web.me.com/pondini/AppleTips/Setup.html