The router came with a Cat 5 cable and I've tried swopping out the PC to router cable with a new Cat 5 (borrowed from work) but it made no difference. Don't have access to a Cat 6 and loathe to shell out more money at this stage.
Netgear support said: -
"I understand that your wired internet connection drops through PC. Regarding your concern, I would suggest you follow below steps to reduce mtu size settings on router:
Change MTU size on the router using the steps below:
1. Open the browser (Internet Explorer or Netscape)
2. Access the router (usually
http://192.168.1.1)
3. Login to the router (User Name = admin Password = password unless you have changed it)
4. Click on the "WAN Setup"
5. Change the MTU size to 1492
6. Click Apply
7. Logout of the router
If the current MTU size does not provide a good result you may try decreasing the MTU size by a random number till 900 to check which ever suits your connection the best. You need not reboot the router after each setup. It is simply required to Apply the setting changes.
It made absolutely no difference. I can see me having to battle with PC World for an exchange to a Belkin!