I hook my ipod up to a stereo receiver and blasted it through some nicer speakers and it was pretty good quality. My Zen was no way better, maybe on par as far as sound goes, but the iPod UI is just better.
I still stand by it. Ok, maybe terrible was a bit too harsh, except for the high frequencies the sound on the ipods is very even, bringing out nice lows and mids. But try listening to a song near full volume, every "s" they pronounce rings in my head and causes headaches. This is definitely not as noticeable when you have it hooked up to a stereo, as the speakers aren't right in your ears. I use my ipod in my car sometimes and it's definitely not near as bad. But damn, when I slap in the earbuds it's unbearable.
As you said, the User interface is great. User input however (on the touch wheels) leaves a lot to be desired. It seems to be hit or miss whether or not it works properly. Also a customizable shortcut button would be nice. It's annoying to go rifling through menus to get to shuffle, especially while driving. And no, the shake to shuffle is annoying as hell.
I've had this on 2 ipod touch's (1st and 2nd gen) and my ipod nano (5th gen). I don't get this from any other branded mp3 player with those headphones, be it the zen or my sony cell phone.
On Topic:
I forgot to mention Asus..they usually make good laptops, with the odd ones being crap. My friend's has serious heat issues. His idles about 30 degrees higher than my Acer, which has the same GPU and a better processor. My Asus EEE and some other ones I've seen are top notch though.
Macbooks are great build quality and have some nice features built in. However, I wouldn't want to use one while on my lap. The Macbook Pro I set up for my friend was too hot to touch on the bottom after some use. She's told me she's scared she'll burn herself on it, lol.