If the question you looked at was the one where I posted some links, the information you require was there - it's just that DVLA don't make it particularly clear!
On this page
http://www.direct.gov.uk/en/Motoring/OwningAVe hicle/HowToTaxYourVehicle/DG_10012524
the tables headed TC49, TC48 & TC59 all refer to cars registered from 01/03/01 onwards. For all other cars, you need to refer to the first table, TC11. That's because, for cars registered prior to March 2001, the tax is assessed solely on a car's engine size, rather than on the CO2 emissions which provide the reference points for more modern vehicles.
Thus, the tax for the Ford Focus will be �180 for 12 months or �99 for 6 months.
As Almcd007 states, you'll need to check the exact specification of the Peugeot, using the link that he/she has provided, to find the CO2 emissions. Then use the relevant table from my link to find out the tax.
As an example, I've just checked the emissions for a 1.6 litre, petrol Peugeot 205 CC with M5 transmission and 120 bhp. The CO2 figure is given as 155. Table TC48 shows an annual road fund tax figure of �140 (or �77 for 6 months).
Chris