情報のまとめ

SV03SP1DDK → Windows Server 2003 SP1 DDK
WDK (6000) → Windows Vista RTM WDK
WDK (6001.18001) → Windows Server 2008 RTM WDK
wlh → Windows Vista SP1 と Windows Server 2008 (x86, x64, ia64)
vista → Windows Vista (x86, x64 SP無)
wnet → Windows 2003 Server SP無 (x86, x64, ia64)
wnet+ → Windows 2003 Server SP1 以降とR2 (x86, x64, ia64)
wxp Windows XP SP1 (x86)
wxp+ → Windows XP SP2以降 (x86)と Windows XP (x64)
w2k Windows 2000 SP4 (x86)

■参考
http://www.devdrv.co.jp/windows/