This Shabbat is Shabbat Zachor, the Shabbat in which we remember tribe of Amalek, the nemesis of Jewish people. Amalek is described in Bible as attacking the people of Israel at weak places and at weak moments.
There are two different ways of reminding us that Purim is around the corner. One is the PR method, involving newspaper ads, thousands of fliers and large street banners, usually advertising the upcoming Purim carnivals. The other involves no media or marketing but has existed for more than 2000 years. It's called Shabbat Zachor (the Sabbath of Remembering).