i've got a t reg 99 vectra and just replaced the driver side headlight bulb. on the 99 reg take the cover off then pull off the connector to see the 2 prongs of the bulb, the bulb is held by a metal prong which if you push in on both sides at the top of the prong then sideways it will release the bulb. hope this is the same for you guys and this is of any help.
steve m, March 2007