If it's available in the UK, I'd be very surprised if it wasn't available in the US. Going to be making a note of this...I get WiFi on my HP Compaq DC5000 SFF via a Netgear WN111v2 USB adapter; we had originally gotten it for my grandfather (God bless his soul, may he rest in peace) a few years back when my family and I attempted to get him online so he could reconnect with some of his old Korean War buddies. It didn't work out as well as we had hoped, but we stayed close until he passed away last year. Among a whole bunch of other things I inherited the laptop we'd gotten him (a Dell Latitude D510) and this Netgear adapter, which I didn't actually use for anything until I got another Latitude (a D830) hooked up to run Windows XP again. The wireless card inside that Latitude had died, and as a replacement I tried the Netgear adapter. It not only worked perfectly but also works with Win2000 too.
I'm hoping to acquire another WiFi adapter in the future, hopefully around Christmas or so; I usually budget $100 for Christmas, and if you're frugal enough/know where to look that can actually buy you some pretty cool stuff! If the price is right I'd like to try and get this dongle along with another PC if there's enough left over in the budget for 1. Thank you for the recommendation, Mike!