LAN v Wireless Connection

First and most simple suggestion - try a different cable. They can cause problems sometimes, particularly if they're in a room which gets cold at night and warm in teh daytime, or if they're caught under a piece of furniture.

Thanx for that but tried a different cable and no better. Even tried old cable in laptop and run that through the router and there was nothing wrong with the connection, so it looks more likely my PC is at fault, but cannot work out why. Hate to think that i'm going to have to reinstall Windows so any advice would be appreciated.

I'm always leery when it comes to people's "perceptions". Let get some real numbers before proceeding any further. Go to http://www.speedtest.net and test with wire and wireless, then post the results.