Go the WD all the way. I work at a computer store, and we have dropped Maxtor, we have had more than half of the Maxtors we sold in the last two months go bad, we're replacing them with WDs.
THe WD is also known as one of the fastest drive out right now.... go for it.
The ATA100 vs. ATA133 is a moot arguement. The truth is they barely saturate the ATA100 standard. ATA133 is just a PR campaign to sell more drives. In reality the WD is the faster drive.