Today is Budget Day.
Unlike most budgets, the details of this one have been pretty well leaked or can be reasonably guessed.
The BBC has a list of guesses/leaks here Budget 2011: What we already know.
As to whether this budget really does stimulate growth, depends very much on people's "optimism/pessimism" about the future.
Given that many expect interest rates to go up, George Osborne may well have a difficult task kick starting growth no matter how much he tinkers with personal allowances.