I noticed that the LM hash of the same password on WinXP is different than the one on Win 7. Using Metasploit (run hashdump) for example with the password "pass-w0rd", we got the following hashes:
WinXP:
a824903ef6ab871802657a8d8ef025e2:fac374e2461f3e432 cd4c560dd183671

On Win 7 systems, they are all different:
ae6b29b9f354a26d6e29f53173b0c7a1:d4dd8cd6f14c445e0 a16b3c08a2bf341
or
be7248be0caf22327a7798efba346fb7:1a9d81b177c19a206 5eaee8cbe9689ce

Anyone?