Macbook is struggling with internet

I have had a macbook pro for nearly two years.

About a year ago our router started playing up so we bought a new one (NETGEAR router). Ever since buying the router we've had endless problem (Mainly the signal is confined to a short distance) but mainly with the macbook pro. We also have another macbook and a PC in the home which have worked ok with the new router (albeit sitting right next to it!!).

Since Christmas 2011, the Internet hasn't been playing it's best game. The signal strength shows high when clearly it isn't. Occasionally I restart the router but I stray away from that option.

Just in recent weeks the computer has been taking a while to load up certain pages, if not at all. TV programs on iPlayer or ITV take an age to watch.

Yesterday, I re-installed Mac OS X and still nothing has changed. I thought it was perhaps something that might have been downloaded but this particular laptop is not used for that kind of purpose and still has 200 GB left to play with.

I have tried numerous browsers, recently trying out Chrome. That doesn't change anything.

I have restarted programs, cleared history, trying I think, absolutely everything possible to search out the problem.

Aside to this the other computers on the network are still working reasonably well.

The macbook pro is hardly used for any strenuous jobs as it's a laptop specifically used for Childcare purposes. However when children want to use the computer to watch programs or play games, it doesn't work.

My last resort is to probably take the laptop back to the store and see what they can make of it.

If anyone else has any other help it will be greatly appreciated!

Mainly my query is wanting to know, whether this is a problem with the laptop or the router.

Thanks.