Do I need to upgrade to get iTunes 10, or can OS X 10.4.11 run it?
Your iBook G4 can not run Snow Leopard, because of PowerPC G4 chip inside. Snow Leopard require an Intel chip. You can get iTunes 10 to work on your computer, just upgrade to Mac OS X 10.5 (eBay or so... buy full retail version, not gray discs).