Well, to many people, running Windows or not will be thing of the past. Especially if all they do is write emails, browse the web, listen to mp3s and watch video clips (not DVDs).
To me, the current Zaurus OS/hardware has one major trumpcard ... actually two-in-one:
InstantOn + Long batt life
I have a collie and I don't find it slow at all, so I think a C1000 hw would be pretty zippy already. If so, it would be an excellent device for many folks.
Vadem CLIO and the other HPC OEMs failed in a sense, not because their products sucked, but because they never quite intended or marketed them for end-users. HPCs were targeted at verticals right from the start.
MS, Intel and UMPC partners are gauging the market very gingerly to decide where to target it. MS stated a $500 bottom price and I believe that was a crucial factor for the subsequent BUZZ.
Vadem and the other HPCs failed because they mostly came in at around $1000 and were intended for verticals. If they had made bigger bets and priced them at $500 back in 2000, maybe the PC landscape might be quite different today. Maybe HPCs might be 30% of the market while desktops and notebooks the remaining 70%.
I believe MS and its croonies kinda signed Vadem and HPCs to their death with the $1k pricing and today, UMPCs (I like Origamis better) will die a same fate if they do not peg their price lower.
I believe Origamis can deliver on the $500 pricetag, but it may be awhile before they do on the battery life. If Sharp or someone deliver on an Origami with a $500 pricetag with a 5~6" screen in the Zaurus clamshell design, they would win.
Last note on why Windows or not, it won't matter. The most popular MP3 player on Earth does not run Windows or a variant of Windows. And its not even from Microsoft. Apple proved that if it does what users want, at the right price, users will lap it up. ... and you do not even need to have the Windows Start Button!