Well here are a couple of sites that talk about networking with QEMU.
If I may suggest provided you are on Intel or AMD hardware that you use VirtualBox, or VMWare Player, it will be much easier to setup and use. VirtualBox offers many features, one of which is out of the box networking to the internet via a NAT device for the guest OS. You can also use a host interface that creates a tap device you can bridge to your real wired ethernet, and VirtualBox has excellent documentation. OR VMWare will provide device interfaces for you as well, it is very good with networking. I also am experienced with xen and even that networking is easy if you have a wired connection to your router. If you are using a wireless card or want some other setup for your network configuration, look at my two recent blogs on VM networking at http://www.myspace.com/scheidel21
they are not the greatest step by step guides, but they give you some ideas.