I found a download to a beta version of MSN Explorer. it’s still hosted in Microsoft’s website for some reason. URL is http://download.microsoft.com/download/msninetaccess/Install/preview1/W9X2K/EN-US/msnsetup_full.exe
As for Preview 2, I doubt I can find it anywhere, therefore it looks identical to the final version.
here is a webpage that went through this version during that time in mid 2000 http://www.activewin.com/screenshots/images/microsoft/msn/msn_p1.shtml