well, if its just the water pump, i think you should be fine. There is a few problems that occur t out BMW e36 that its considered "normal". Like water pump, some sensors, brake light switch. The original water pump come with a plastic empeller nad it means... IT WILL BREAK. u need to get one with a metal empeller like this one: "http://www.pelicanparts.com/cgi-bin/smart/more_info.cgi?pn=11-51-7-527-799-M52&catalog_description=Water%20Pump%20(uses%20met al%20impeller,%20includes%20O-ring),%20323i/is/iC%20(1998-99),%20325i/is/iC%20(1992-95),%20328i/is/iC%20(1996-99),%20M3%20(1995-99),%20Each%20%09%09%20"
I had the same problem but mine pump died and the car didnt and it started to over heat.
Fingers crossed to be jsut the water pump! =]
PS: I love my BMW too hehehe
PS2°: I recommend you to check out the list of common problems with e36, im in a hurry now, if u cant find, ill try to post it soon. Its really good ideia to be aware of what can happen, so u can prevent something like that, (by having a new one and/or replacing before it breaks) and learn about the car, and u'll see how good BMW is.
Good Luck dude =]