Ultra ATA compatibility ? w/ Hitachi ATA-6 vs Seagate ULTRA ATA/100

My 1gz G4 Powerbook 12" is Ultra ATA.

I want to replace the hard drive with a 100GB 7200 rpm


Will the Hitachi ATA-6 work in my PB?

I assume the Seagate ULTRA ATA/100 will work. Am I correct?

If both work, given that the Hitachi is quieter and better on some speeds is the add'l 2-year Seagate warranty (5 years vs Hitachi's 3 years) worth the extra $100 pricetag?)

(Anyone have any experience pro/con with a Seagate Barracuda?)

THANKS!