When you run mac/windows side by side is it possible or even necessary to run windows specific and mac specific anti-virus software? or ideally would any type mac protection also cover the windows side? or vice versa?
It should suffice to run Windows AV software on the Windows side.
For Mac OS X please read the following FAQ:
Mac Virus/Malware InfobyGGJstudios There are currently no viruses for Mac OS X in public circulation, only a handful of trojans and other malware, which have to be installed manually via entering the administrator password.
The only anti-virus you need to protect your Mac is education and common sense.