To enable Windows Vista to connect to Mac OS X with Windows File Sharing enabled, you will need to change the following policy in Windows Vista:
1. Click the Start Orb, type gpedit.msc into the
Start Search field, and press Enter
Click the Continue button on the User Account Control prompt.
This will launch the Group Policy Object Editor for the Local Computer Policy.
2. In the Group Policy Object Editor, expand:
-> Computer Configuration
-> Windows Settings
3. Open the 'Network security: LAN Manager authentication level' policy and change the Security Setting to:
Send LM & NTLM - use NTLMv2 session security if negotiated
4. Click the OK button to save changes, and then close the Group Policy Object Editor.