Hi to watch sat tv using a Sky box can I use a Monitor or does it have to be TV?

a sky box outputs audio and video two ways
via the rf conencion
via the scart connection

i do not know if there are any adaptors for converting either of these two to a VGA connection on a standard monitor,

some of the newer LCDs / monitors have component connections (ie red yellow and white) which can be connected using a scart to component cable.

Some of the more expensive monitors have suitable inputs.

I have a Dell monitor with composite, component and S-Video inputs. I have my sat system and DVD player connected to it as well as two PC's.

It's also worth noting that some of the new sky boxes like SKY HD and possibly SKY + have HDMI which you can get a hdmi-dvi converter which will work in pretty much most LCD/TFT type monitors.

Of course if your current monitor has HDMI connection then you don't need the DVI converter.

Many of the cheaper monitors still do not have DVI input - check the specs carefully!