Moving from G to N

I have a wireless-G adapter that I use currently with openSuSE; the router also supports wireless-N, and I would like to move to an adapter that matches the router. The current adapter is USB (despite this being a desktop) and uses WPA2 (which I would rather keep). What is the best wireless-N adapter that matches the feature set?

I don’t know about USB 11n adapters, I bought a 11n one from ebay but it’s such a pain to get it working in Linux that I just bought a PCI wireless one - TP-Link WR851n, works out of the box in Linux and has Win 7 and Win XP drivers.

This PCI wireless has two ariels and is a 300Mbps version, plus it’s like £16 from ebay, brand new.