In january/february, Windows 2003 had a major bug in the Jet driver. That caused ASP sites using the jet driver to crash regularly and it affected alot of hosts.
Microsoft issued a hot-fix for this issue in July and we have that installed on our win2003 servers and hence we are confident of no issues.
HSauth and HTaccess, two hsphere modules we believe are also responsible for IIS crashes have been disabled from our win2003 servers