I have setup a new connection with the router connected to the computer and i am getting a good speed connection about 4mb which I am happy , but as soon as i go modem>router>computer it drops to about 2mb.
That is very unusual i guess there is something wrong with your router.Just maybe check they match the settings virgin media give you.However, i doubt this will be the problem best bet just to email them as they will know more about it than me.