But Tory leader David Cameron said the Government was "desperate to go on a borrowing binge," which would have to be paid for by tax rises later.
Ahead of next Monday's critical Pre-Budget Report, the Prime Minister said there would have to be "fiscal expansion" to help hard pressed families and businesses.
He branded the Tories the "do nothing party" and said fiscal expansion was needed to bring back growth into the economy.
Mr Brown said: "We are going to be the party that helps people through this difficult downturn.
"The Conservative Party have changed their policy yet again and now they are unable to help people."
And he warned the Tories again against "talking down" the pound and spoke of the perils of deflation.
During Prime Minister's Questions, Tory Philip Dunne demanded: "Can you explain why the pound has lost over a quarter of its value against the US dollar in less than four months.
"Do you still believe what you said in 1992 that a weak currency arises from a weak economy, which in turn results from a weak Government?"
Amid Tory jeers, Mr Brown responded: "I would advise Conservative Members not to talk down the pound.
"And I would advise Conservative Members to take the advice of Lady Thatcher, who said that trying to help the speculators and talk sterling down is the most un-British way."
Challenged by Labour's Gordon Marsden on the need for action to help people hit by the economic crisis, the Prime Minister said: "I think what people want is real help for families and businesses now.
"People are beginning to understand that what is happening in the global economy is that while last year we had a major inflationary problem because of oil prices and food prices - in the coming year inflation will fall.
"It will enable us to put fiscal policy in support of monetary policy - and what I mean by fiscal policy is real help and real support to families and businesses now.
"That is the way for the economy to grow in the future."
Wednesday, 19 November 2008, 15:55:09