teerex:
I bought the usb adapter version of this (though without draft-N capability) for £12.99 from Play.com and it works a treat.
I don't understand the "homeplug" business - what's that all about?
Homeplug, or powerline, as it's sometimes called enables you to use your domestic electrical circuit as a wired network. It's more secure then wireless because your network is only within your property and it tends not to drop and isn't as prone to fluctuations in speed.
You'll need two homeplug devices to start with. You simply plug one into a power socket near the device you want to network and run an ethernet cable from the homplug device to the device to be networked - like a PS3. You then have to do the same thing with the other homeplug device but connecting it to your router.
The only downside is that it's not so mobile. So unless you've got a very long cable you wouldn't really be able to sit out in the garden with a laptop like you can with a wireless setup.