Hi
AGENTKB, it depends whether your Vectra C is fitted with IDS+ (Interactive Driving System).
IDS is the standard default suspension set up on all Vectra C's (and Signums) using lightweight front MacPherson struts and multi-link independent rear suspension.
IDS+ is as IDS, but with the addition of Continuous Damping Control (CDC) and a 'Sport' button, which 'tightens' the suspension. Only VXR models were fitted with IDS+ unless the vehicle was purchased new with it fitted as an optional extra.
I believe the Vectra C and Signum had the same front axle and suspension setup, so if the part your showing is not for IDS+ and your Vectra does not have it either, it should be a correct part.
Best to check with the supplier before ordering, and if the wheel bearing is shot one side, you can be sure the other side will follow soon after, so best renew in pairs.
I'll post up some part numbers for cross reference later..
Hope that helps.