SEP  MR4 and above can be installed on Windows 7 but it is not supported. SEP MR5 will support windows 7 and 2008 server R2

Best Regards.
Fatih

Release Update 5 (RU5)

What's new in this version
The current release includes the following improvements that make Symantec Endpoint Protection and Symantec Network Access Control easier and more efficient to use.

Symantec Endpoint Protection Manager now supports the following operating systems:

• • Microsoft Windows Server 2008 Service Pack 2 (all editions except for Itanium)
  • Microsoft Windows Server 2008 R2 (all editions except for Itanium)

Symantec Endpoint Protection Manager can now be used with Microsoft SQL Server 2008.

The Symantec Endpoint Protection or Symantec Network Access Control client now supports:

• • Microsoft Windows 7 (all editions except for Itanium)
  • Microsoft Windows Server 2008 R2 (all editions except for Itanium)
  • Microsoft Windows Vista Service Pack 2

http://service1.symantec.com/SUPPORT/ent-security....

Note:
installing  unmanage client on windows 7 just make sure firewall is turnoff sometime it rollback installation because windows 7 firewall block some ports.

About Symantec Endpoint Protection support for Microsoft Windows 7 and Microsoft Windows Server 2008 R2

http://service1.symantec.com/support/ent-security.nsf/854fa02b4f5013678825731a007d06af/b09d685c029bec68882575ec0076f089?OpenDocument

Support for Symantec Endpoint Protection on Microsoft Windows 7
http://service1.symantec.com/support/ent-security.nsf/854fa02b4f5013678825731a007d06af/bdfc2358fdbb84b488257515006de78c?OpenDocument

What works and what is supported are two different things.  
While MR4 may work, not all components did.  

RU5 and greater are the supported versions for Win7.