I would pressure test the system (it should be obvious then); as noted in other threads, you can get a pressure test kit or make your own, using the stock tank cap/valve to connect to a pump. If you don't have the cash for the repair; bypassing the heather, until you do... makes sense.
More info: http://newbeetle.org/forums/1-8-liter-turbo/78553-2000-beetle-mystery-coolant-leak.html
More info: http://newbeetle.org/forums/1-8-liter-turbo/78553-2000-beetle-mystery-coolant-leak.html