May 5th 2010 will be just fine for the root servers cut over to DNSSEC
To see if your Windows 2003 server is using EDNS:
dnscmd.exe /info /EnableEdnsProbes
If it things don't go so well on W2K+3 you can just disable EDNS:
dnscmd Server Name/Config /EnableEDnsProbes 0
If you don't have the tools installed:
http://www.nthelp.com/w2k3/turning_off_edns.htm