Simple enough IMO- they are just trying to release the products slowly to make more money and take less risk. e.g. Portable Video Players have been around for years but Apple slowly increased the iPods strengths to a different tempo rather than releasing it all at once.
More chance of getting people to upgrade, especially if your effort to make something simple have paid off in that it really is simple to use and well made- also I guess there are less R&D costs for not making an all singing all dancing version.

Exactly the problem for Archos- none of there stuff is unbearably out of date because it was generally really well made in the first place, the main way they get new sales is by people showing theirs off to friends whereas Ipod sales come a lot from previous owners... sucks to be Archos at this point.

P.S. The AV500 kicks ass and my girlfriend just got the 504- three days ago, this news will break her heart!

@ xxdesmus

Tablet PCs may not be doing fantastically but Vista is a much better OS for the platform. Their reach has been limitted in my opinion because of low publicity, my family owns two I am using one now, I know a few people who are interested so this is important to some people.