For Europeople, you need 400 for Silver and 800 for Gold.
Note: once you reach Silver, your points get reset to 0 and then you have a year to make 800 for Gold; you cannot qualify for Gold by reaching 800 points in one year.
In the UK, the threshold is 600 for Silver, 1500 for Gold.
Clearly set out here for UK members:
and here for Europeeps: