To see the ext3 partition in Windows you need special drivers.
http://www.fs-driver.org/
About how the file systems work. Here's alot of links to different filesystems and how they work:
http://en.wikipedia.org/wiki/File_systems
http://en.wikipedia.org/wiki/Comparison_of_file_systems
http://en.wikipedia.org/wiki/List_of_file_systems