Win XP running under Win & proffessional

[#1]

I am running Windows 7 professional, which runs nearly all of my old 3.1, 98, XP programs successfully. However, one refuses to install under Win 7
I plan to install Win XP mode so it runs under a virtual XP pc, inside win 7.
I have Plusnet/McAffee  virus protection on my Win 7.
Will this also protect me whilst I'm using the virtual XP ?

[#2]

You need to add a separate AV that supports XP

[#3]

You won't really be any danger whilst running the virtual Windows XP unless you start surfing the net or reading emails - and why should you want to do either of those?