How often should I get my car serviced?

I have a 1996 Ford Festiva 5 door manual. Its a great little car and I have no problems with it. However, now I have moved, I use it very little during the week. It would only maybe do 80 -100 kms. per week. Some tell me because I use it less it needs servicing more often,. Do I really need to get it serviced every 6 months as my local serviceman recommended. If not, then how often would you suggest. It is parked in a carport in a block of units, so pretty well protected from the elements.