The Guardian has an interesting feature article by Andy Beckett, attempting to address the question above. The obvious answer is yes - and indeed that's the answer offered by Beckett and a number of those he interviewed for his piece, one of whom suggests the collapse of Lehman Brothers in September 2008 was the great test (and we failed the test).
While I broadly agree with the thrust of the article, it's worth first noting a serious problem. Beckett appears to overestimate the opportunities we can expect to have due to economic crisis. The current crisis has a generated a complex situation, ideologically and politcally, and it inevitably won't all go the way of the radical left. Other forces, like the mainstream Right (e.g. Cameron's Tories) and the far right (e.g. BNP) can exploit the disillusionment and anger created by the crisis.
Beckett's article will resonate with people, however, because a crisis for capitalism is bound to prompt discussion of what can be done about it - and what alternatives exist. At least at the level of ideas, a crisis for the whole global system - and collapse of the ruling ideology of the last 30 years, neoliberalism - must open up new opportunities for the radical left.
Several months ago mainstream papers were reporting that there had been a renewed interest in Marx, citing a surge in sales of his masterpiece Capital and a number of lesser works. Neoliberalism's collapse doesn't automatically mean people reject capitalism altogether, but it does at least create a space in which Marxists can debate with people. In this context should we be doing better? Yes we should.
Of course it is an objective difficulty that the level of class struggle remains relatively low, despite the inspiring stirrings of revolt from workers at Waterfords, Visteon, Vestas and Thomas Cook, all sites of militant occupations. This prevents rapid and mass growth of socialist organisations.
But a time of raw working class anger at capitalist greed and questioning of the system, against a backdrop of years of what might be called a 'political upturn' (anti-capitalist and anti-war movements, mass rejection of New Labour's rightwards shift), should be fertile for the left. So, yes we can do better.