ok thanks guys i found the satnav on ebay its a philips and the add says
* VAUXHALL OMEGA SAT NAV DISPLAY
* REMOVED FROM A 1999 TOP SPEC CAR
* PLUGS IN TO THE DASH
* EXCELLENT CONDITION AND PERFECT WORKING ORDER
if it will be a lot of trouble i wont bother just though it would be a nice addition 
Is your car a facelift or prefacelift?
How bad! I dont know the difference sorry new to the omega world
Is your grill attached to the bonnet or is it seperate?
Its seperate so i assume its pre face lift then?
Sounds that way - does your dash look like mine (in that link posted earlier)?
yes the dash is the same 
CARiN was the factory fit option then. Bit dated now, but can be picked up cheap. Pictorial only (ie, no 'map view' like Tomtom etc).
It is possible, as you can tell from that thread, to pick up a Siemens system, which is what I have in mine now (in addition to the CARiN). Lot of work to fit that in the prefacelift though.
thanks for your help mate just 1 last question where's the best place to look for the CARiN ones