I'm wondering why you have had the Macs access the Windows servers using SMB. Mac OS X has Samba built in so you should be able to connect to the Windows server that way. If you want to configure more options, you can head to Applications-->Utilities and bring up Directory Access. There, you can configure things like NT domains and Active Directory.
• Apple iMac G5 17" (2 GHz G5) - Mac OS X 10.5.8/Ubuntu 10.04
• Asus Eee PC 901 (1.6 GHz Atom N270) - Fedora 13
• Apple Macintosh Quadra 650 (33 MHz MC68040) - Mac OS 8.1
• "JHVH-1" (2 GHz AMD Athlon XP 2400+) - Slackware 13.1