The first thing you should do is take a speed test with a direct cable connection from computer into router (i.e. non-wireless, like the old days) - this will give you a more representative set of results. It could be that you are a bit too far from the router, or it is struggling to get through thick walls (or typical Turkish concrete walls full of reinforcing steel which are no fun either). Once you know that set of results you can compare them to the ones above (which are appalling by the way!) and get a grasp of what is being delivered to you, and what is being lost with your own in-house wireless setup.
If the figures are better when using direct connection, you are losing too much on it's next journey from router to computer - this can be for thee reasons given above but also check other things too - like keeping your router away from the telly, sounds daft but it was a problem I had and that solved it.
I have quite a distance between router and laptop myself (I don't have a big house, I have a long house

) and the two things are at directly opposite ends - I tried one of these silly little things on a recommendation and my signal indicator went from 1 or 2 bars to 5 and that was the end of my problems:
http://www.amazon.co.uk/gp/product/B003MTTJOYEverything sorted for £9 and sorted in 10 seconds by putting it in and letting it install itself - but that was down to the problem being my setup & home - which is why a direct cable connection speed test will tell you everything you need to know. Good luck.