USB vs PCI adaptor

I'm awaiting delivery of a new virgin media N wireless router. The bit i'm having trouble with is finding of there are any differences in performance of a USB adaptor or a PCI card adaptor for a desktop PC. It'd be lovely if anyone could let me know. But there's a bonus question too, can I use a cable from my router to my PC instead of buying a new wireless adaptor? This would be the most convenient, but I can't find the information anywhere...

[Admin]

All routers should allow connection to your PC using network aka 'ethernet' or 'cat 5' cable. All modern computers and laptops should include a network/ethernet socket.

As for wireless adapters, the type of connection shouldn't make a difference in performance, barring that more expensive PCI adapters can larger aerials and that USB is easier to install. However I'd recommend that you read customer reviews before buying any adapter as in the past G-rated adapters were of variable quality.