Ok first of all, forget about the ATA 133 vs. ATA 100. The difference isn't as big as you would think.
I always by WD. They have been extremely reliable to me (As opposed to Maxtor) and this is the only reason why I buy them.
I believe a hdd should be bought for its reliability first, then performance, then everything else. Because after all, important data will be stored on that drive and I'm pretty sure that if I give you the choice between:
a) the security of your data
or
b) the speed at which you access your data
you will probably choose a) (at least that's what you should do).
for that reason, I choose WD any day over any brand.
That being said, Maxtor isn't bad at all. some people have had very good experience with them and very bad experience with WD. However, I can't see myself recommanding anything but WD. Even if it's slower than Maxtor and even if it's louder than Seagate. And when I say slower or louder, it's nothing dramatic and you probably won't notice it.
I'd say that the difference in speed between ATA 133 and ATA 100 is the same as between single and dual-channel for the Ram or AGP8x and AGP 4x for video cards: it's nothing to write your mother about.
And about the noise..I'm pretty sure you have louder things than hdds in your system so donT' even think about that particular characteristic.
