I know that these devices aren't new, but I've never used them before today: D-Link's Powerline network adapters are superb and a great way to extend your network to those hard-to-reach WiFi spots.
Setup time is minimal (around ten minutes with all the plug & sorting and cable untangling!) and connecting your PC to the network gives new meaning to the phrase plug 'n' play. All-in-all I'm very impressed.
Just one word of warning: the RJ45 cables supplied in the starter kit are around 450mm long (around 18") and nowhere near long enough for any practical purposes. Make sure that you've got a couple of spares handy or buy some when you order your starter kit.
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