I've been looking at getting a Epia MIIE6000 myself.
Ability (abiet extremely limited) to hook up laptop-style LCDs, low power usage, quietness, convenience.
Sure it has then horse power of a 300-400mhz Pentium, but so what? I can get firewire, USB 2.0, 1gig of ram, any harddrive of choice. It has a onboard mpeg2 decoder for smooth playback, it can handle divx file fine, it can surf the internet fine. It can support cardbus and flash cards...
So what more do I need? If I want horsepower I just turn on my 2400+, but normally I don't need the annoyance of hearing it's fans blow and the sucking sound on my wallet from the electrical bill from leaving it on all the time.
For 80% of what I do, I'd be happy with a low power desktop with all the niceties of a modern machine just without the annoyances. Plus I can hook it up to a nicad battery pack and carry it around with me if I feel like it. 9000mah 12v battery pack of Nimh cells will run that thing for at least 6 hours, costs only 90-110 bucks and would weigh only couple pounds.
Or I could hook it up to a lead acid sealed battery that I can get for 50 bucks and have it run for 10 hours, take it out on the boat or whatever, or hook it to my car and have it run for weeks.