which win32 builds to get?

[Frank Burleigh]

I always get mozilla-win32-installer.exe, but yesterday (in the context 
of adding a comment to a bug report) I noticed that I had 2001051804 
with exe and DLLs dated early afternoon on the 18th.  So then I tried 
mozilla-win32-sea-installer.exe which produces software with a "new" 
build number.  Would someone clarify the builds in the "nightly" directory?

Also, I've heard talk of a net installer for win32 but don't see that 
anywhere.

Thanks.