Thanks for the reply you two.
chickendippers, good job you got me to check the screen settings on the TV when it is tuned onto Virgin TV. It turned out that unlike my freeview (and I think also my older game consoles) the screen wasn't automatically set to 'Auto' rather, the TV was displaying programs in their broadcasted ratios.
I think I will upgrade to the XL package, it is just a shame there is no chance of getting a faster set top box. Thanks again!
Does anyone know, roughly, how my SA 4200DVB would perform against a standard sky box? In terms of things like channel changing etc?
Pia don't worry about it! i'll make sure i stop the rain when i want to watch TV.