I've run into the need for these articles on the .Net garbage collector a couple of times in the past month - I thought I'd blog them so I know where they are. The first two were written prior to .Net's release by Jeffrey Richter. The third article is a nice discussion on the impact of design choices related to the garbage collector.
http://msdn.microsoft.com/msdnmag/issues/1100/GCI/TOC.ASP?frame=true
http://msdn.microsoft.com/msdnmag/issues/1200/GCI2/TOC.ASP?frame=true
http://msdn.microsoft.com/library/en-us/dndotnet/html/dotnetgcbasics.asp?frame=true