not so much. with a virtual machine, you arent using your native hardware at all except to help run the virtualization. you use hardware that the vm virtualizes for you, including network, audio, and graphics.
you have limited 3d graphics acceleration, so goodbye gaming.
also, most vm's are based on old audio drivers, so sound quality can be limited at times.
You are using your native hardware, except with a virtual layer over it. The software isn't emulating hardware, which is why they are called virtual machines and not emulators. The 3D performance is mainly due to the lack of Direct X support in virtual machines. Last I read VMs were fully DX8 compatible.
The NICs are generally just virtual bridges of your actual NIC so they don't need drivers, which is not a big deal. Servers run tons of virtual NICs all the time.
Performance, yes it will perform less, but it is getting better each day. When you run native Windows apps on a Mac or Linux box with CrossOver it is not a virtual machine at all, it is a set of APIs that run in an enclosed "bottle" that fool the app that it is running in Windows. WINE is an example of this as well. Those apps tend to run just as good for the most part.
The only time you get major performance hits is when you try to do something very taxing like 3D work, or gaming, or heavy graphic design. All other basic tasks run just fine.
