some really good screen casts(videos) to learn SharePoint

http://sharepoint-screencasts.com/ and http://msdn2.microsoft.com/hi-in/library/bb892193(en-us).aspx links has got some really good & short videos on MOSS/WSS3.0. Good for beginners.

SharePoint Architecture, excerpt from Inside Microsoft Windows SharePoint Services 3.0 book

Here I found two articles on Sharepoint Architecture and Page Design, infact these are the excerpt from Inside Microsoft Windows SharePoint Services 3.0 book by Pattison and Daniel Larson.

SharePoint Architecture:
http://msdn2.microsoft.com/en-us/library/bb892188.aspx

Pages and Design:
http://msdn2.microsoft.com/en-us/library/bb964678.aspx