MTU Confusion With New Router

I have just purchased this ADSL Ethernet router:

Extra Value 4 Port ADSL / ADSL2/2+ Modem Router - Ebuyer

When I configured my Internet connection on here I found that I could not access some websites. For example:

Microsoft.com
MSN.com
Windows Live Messenger, etc.

I did some research into this and I figured that I could change the MTU settings on the router and then change them on the computer using drtcp.

I change the router MTU settings from 1500 to 1492 and then I did this on drtcp. It works fine on this machine, however any other computers I connect to this router they will not display microsoft.com or anything like before.

I don't want to be going around changing the MTU Settings every time I add another computer to this router, so is there a setting I could set on this router that it I can connect any machine to it and it will just work.

My Internet connection is Orange Broadband, if you need any other information please let me know.

Make sure that your router does NOT have a lower MTU than the PC.

Keith