I strongly recommend installing antivirus software, there really is no reason not to nowadays.
If you are running realtime antivirus scan (recommended) MS suggests exclusion of the following folders:
C:\windows\SoftwareDistribution\Datastore\Logs\res*.logC:\windows\SoftwareDistribution\Datastore\Logs\res*.jrsC:\windows\SoftwareDistribution\Datastore\Logs\edb.chkC:\windows\SoftwareDistribution\Datastore\Logs\Tmp.edbc:\windows\Security\Database\*.edbc:\windows\Security\Database\*.sdb c:\windows\Security\Database\*.logc:\windows\Security\Database\*.chk c:\windows\Security\Database\*.jrsC:\ProgramData\NTUser.polC:\Windows\System32\GroupPolicy\Registry.pol In addition I exclude the Cakewalk Content and the Cakewalk Project folders and:
C:\Program Files\Cakewalk\SONAR X3 Producer\SONARPDR.exe
When it comes to antivirus software there are tons of opinions, so rather than rehash the same thread please read:
http://forum.cakewalk.com/Microsoft-Securtiy-Essentials-m2947912.aspx I never turnoff antivirus except when I get a troublesome software installation.
Cheers
Alex