If Wi-Fi isn't suitable, HomePlug AV might be - this is a industry standard that sends Ethernet signals across standard electrical wiring. Such devices usually resemble oversized plugs with an Ethernet socket and some indicator lights.
My previous experience with such products has been mixed. While HomePlug AV nominally provides 200Mbps, the actual speed will be less than that. How much less depends on your wiring, any sources of interference, whether you can plug the devices directly into a mains socket (their size means they may foul an adjacent socket, so that's not always practical), and - presumably - the quality of the specific product.
And that brings me to D-Link's DHP-307AV, a starter kit providing a pair of DHP-306AV adaptors - you need two devices you need to get going, one for each end of the link. Running between two power points that had yielded indifferent operation with other similar products despite fairly new wiring, the D-Link adaptors proved equal to the task of streaming 1080i video. The reported link speed was usually around 80Mbps.
While functionality is a primary requirement, cosmetics do come into the story to some degree. The adaptors are more stylish than some other brands, but they are still quite large. If the other half of a twin outlet is occupied by anything other than a normal plug (no plugpacks, no surge protectors) you may need to use a double adaptor under the DHP-306AV to provide sufficient clearance. Another potential problem is that an outlet close to the floor may not sufficient depth for the DHP-306AV.
A welcome touch is that the unit goes to sleep if there's no Ethernet activity.
In common with some other HomePlug AV devices, the DHP-306AV features push-button security. The adaptors work out of the box, but if you want to change the encryption key (eg, in case the signal leaves your premises) all you need to do is press the button on one, and then do the same on the other within two minutes. This generates and shares a random key, rather like WPS does for Wi-Fi. Or you can use the included utility program to manually set the key of your choice, but you'll need to enter the password of any remote adaptors (ie, those not directly on the same Ethernet network as the computer), and that 16-character code is shown in fairly small print on the plug side of the DHP-306AV.
The DHP-307AV performed better in my premises than other HomePlug AV devices I've tried (no names, no pack drill). I was a bit surprised by this - after all, it's supposed to be a standard. Presumably engineering and build quality can make a difference.
Exactly how fast the link runs will depend on a variety of factors, some of which may not be controllable, practically speaking. But it was good to see first hand the technology working at close to the 100Mbps speed of the Ethernet interfaces of the equipment I was linking to.
The DHP-306AV costs $79.95 and the 'twin pack' DHP-307AV is $149.95, though I've seen at least one national retailer advertising the latter at a higher price.
D-Link also offers the DHP-1321 PopwerLine AV Network Router Starter Kit (the router provides Ethernet, Wi-Fi and HomePlug AV connectivity, and one DHP-306AV is included; $199.95), the DHP-W306AV PowerLine AC Wireless N Extender ($129.95), the DHP-346AV PowerLine AV 4-Port Switch (to save adding an external switch to a DHP-306AV when you need to connect multiple Ethernet devices; $99.95).