It sounds like your hydrolic tappets are making the noise. Check your oil level properly. If it is dangerously low then top it up but do not overfill. Run your engine for 10 mins, let the engine cool and check oil again. If this dosent help then e-mail me and I will tell you about other vectra problems.
trit666@hotmail.com
Kind Regards
Tristan Hanwell
March 2006