The rates are shown here...
http://www.direct.gov.uk/en/Motoring/OwningAVehicle/HowToTaxYourVehicle/DG_10012524
It appears to show a car registered before March 1st 2001 and below 1549cc to have a charge of £125 for a year and £68.75 for half a year.
But it also says...
* Band K includes cars that have a CO2 figure over 225g/km but were registered before 23 March 2006
...and these cars have a six-month rate of £134.75
So it may be down to Government Legislation and the emissions of your car.
Peccavi, May 2010
