Nope, I specialize in cross platform environments, so I like them playing nice as well!
Apple's SMB code is really home grown...very home grown, so the differences between 10.2 and 10.3 could be very large. We were unable to deploy 10.2 in our 2000 environment, but 10.3's SMB worked fine. Out of curiosity, are you using the AD plugin with Kerberos, or are you keeping local accounts on your Macs and then having them manually authenticate for the shares they require?