I'm after a wireless card? either a pci or usb.... but if its PCI has to be for a small form pc.

I've always had a wired connection, but after moving home my office is now on the top floor and the mrs is not keen to have cabling through the house. My office is on the 3rd floor so needing a good card/usb I have a netgear N router and looking for a really good adapter can anyone recomend one please?