Yea, not a fan of Norton either. One way around it is to have a HDD for work and a HDD for play. Sounds like you might be on a laptop, so just leave the HDD door off, and swap out as need be (I did that for years at my last company).
Alternatively, you could package a work system within VMWare or VirtualBox. Run that system in full screen when you're at work, install 360 on that, and your boss won't be any the wiser.