New
#31
Every VM engine worth it's salt gives you full control over how you want to emulate the NIC - disabling it completely is easy as pie - and won't be automagically reennabled. You can manually bork Win7's IPv4/6 configuration settings if you were concerned, so even if it does have interent access it won't be able to get an ip address or connect to anything. Virtual machines have hardware acceleration so you are unlikely to run into a case where a specific application will not run properly in a VM. Really it's not that hard to try out - hell, just install VirtualBox for free and set up a VM with no internet access and point it to your existing Windows 7 partition.
I really think dual-booting is completely unnecessary in this day and age, and is actually quite risky with frequently patched OSs like Windows.