NIS Installed on Win 7 & Xp Mode under 1 License

So Win 7 is hitting and been installing our partner licensed copy playing with XP mode quite heavily and finding XP mode doesn't use the hosts security settings obviously you can disable the network adapter in the settings so that the internet canno't be used minimising the risk. 

However if you wish to use an Internet connection your going to need some security. So basically the question is, i have a subscription at home for NIS will i be able to activate it on my Win 7 machine and XP mode within Win 7 and both work concurrently with no issue.

Seeing as i am on the same PC and i always understood it that the Norton license the 3 user ones cover 3 PCS not OS's then this should be fine but thought i would get some clarification. 

From the CTO of Sophos who said recently:

Jacobs says if you use XP Mode, “now you are managing twice as many PCs as before” and charges that XP Mode “increases cost and complexity.” You may indeed need to install anti-virus software on the virtual OS, but he is quick to point out that “licensing is not a problem for Sophos products.” Sophos is not unique in this; other vendors also license their security software on a per-physical machine basis, rather than per-OS instance.

So is this the case for Symantec also?