Hi,
Check your battery first, it sounds like it's on the way out. If you have a mate with a battery, put it in your car and start it up, then put a meter across the battery terminals. You should have a reading of about 13 to 13 and a half volts if your alternator is good. If your red battery warning light is on with the good battery in and the engine running, you are probably looking at an alternator. You should check all electrical earth connections for corrosion just to be safe though.
Cheers now
Ken Chapman, April 2007