I have a charity who have two adjacent medium sized modern detached houses (in the UK): the buildings stand next to each other and are less than 5 metres apart. They have DSL connected to a single computer in one of the buildings. They want to add a network with wireless, and want it to work across both buildings. Being a charity they need to keep costs down. The network would be used for sharing Word documents, e-mail, browsing and skyping.

My initial thoughts were to connect the buildings with fibre. So:

Option 1 Use fibre between the buildings. Sufficient cable and two TP-LINK MC100CM Fast Ethernet Media Converters. Cost ~£80.00.

But there is the extra cost and hassle of running the cable down and up the external walls, lifting and relaying paving, and burying underground.

Never having fitted fibre I'm also a little worried about going up the wall and then bending the cable at 90 degrees to go through the wall and into the building.

Option 2 Use two TP-Link TL-WA7510N High Powered Outdoor 5Ghz 15dBi Wireless antennas to connect the buildings. There is a clear line of sight at first floor level. Cost ~£100. And much easier to fit than fibre!

Is using the TL-WA7510Ns overkill? Is there something more suitable? I had hoped to use some Netgear stuff, e.g. two DGN2200, one in each house and also use them to provide the wireless link between the buildings. However, in bridge mode wireless client association is not available and repeater mode with client association only supports WEP security which isn't strong enough. Is there something similar that would be up to the job?

Option 3 Connect the buildings with UTP cable. My concerns here are risk of electric shock due to a difference of potential between the buildings (or are they so close this shouldn't be an issue) and protection from lightning strikes. Is fitting lighting arrestors expensive? And what can be done to ameliorate against the risk of shock?

This all falls outside my area of expertise so I would really appreciate some advice.