Don't panic. Your right in your assumption that you will need a PCI network card for your pc. These are a breeze to fit and cost around £10. I have used a belkin card in the past and found it easy to set up and load the drivers for. Like yourself I used it to connect my Xbox live account. Don't skimp on the quality of crossover cable you use to connect the xbox to your pc. I can recommend the cat 5e cables supplied by scan computers for this purpose.