Transfer data from Powermac G4 to new 27" iMac

I have a 2003 PowerMac G4 that I am replacing with a new 27" iMac 3.4 i7 which is on order. I want to transfer my photos and iTunes files to the new machine. I had purchased a LaCie d2 USB3/Thunderbolt harddrive in hopes of backing up the G4 but it is "not supported by this architecture". The G4 was updated to USB 2. The LaCie is USB3/USB2 compatible.

Can I use Migration Assisant going form a pre-Intel computer to an Intel based computer? Is there a Firewire 800 to Thunderbolt or USB 3 cable? There is about 200 GB that I need to transfer.

Any suggestions?

Hardware Overview:

Model Name: Power Mac G4

Model Identifier: PowerMac3,6

Processor Name: PowerPC G4 (3.3)

Processor Speed: 1 GHz

Number Of CPUs: 1

L2 Cache (per CPU): 256 KB

L3 Cache (per CPU): 1 MB

Memory: 2 GB

Bus Speed: 133 MHz

Boot ROM Version: 4.5.7f1

Serial Number (system): XB31102SN1S

Hardware UUID: 00000000-0000-1000-8000-000393CACB46

FireWire Bus:

Maximum Speed: Up to 800 Mb/sec

System Software Overview:

System Version: Mac OS X 10.5.8 (9L31a)

Kernel Version: Darwin 9.8.0

Boot Volume: Macintosh HD

Boot Mode: Normal