In testing Windows Vista SP2 and Windows 7RC1, I've come across some hacks that help make the Os work better with Samba (linux) and CIFS (netware).
1. Change Security network connection from default to LM & NTLM. Open up Local Security Policy editor. Select Local Policy | Security Options. Change Network Security: Lan Manager Authentication Level to Send LM&NTLM-use NTLM2 if session is negotiated.
2. Change RDC. Open Control Panel | Programs and Features. Select Turn Windows features on or off. Uncheck the Remote Differential Compression. This will require a reboot of the workstation. This turns off the adjustments the network makes in talking to shares on linux (or Netware).
3. Disable autotuning. Open a command prompt, Start | Run | CMD to open a dos window. In the window type netsh interface tcp set global autotuning=disabled This must be run as an administrator on the local machine. This will require a reboot of the workstation. This makes talking to the SME server in a web browser much quicker as well as most other internet web pages.
These are the hacks I make on all my Vista/Win7 systems and so far I have only seen remarkable improvement when connecting to SME servers.