"We are well prepared and completely determined to get to the top," he said at the launch of the new FW25 car at the Circuit de Catalunya.
"We have a new, innovative chassis as a product of a completely different way of thinking. And with the P83, BMW has developed another new and more powerful engine.
"With Juan Pablo Montoya and Ralf Schumacher we have two winning drivers," he added. "Moreover we have been very impressed by the performance steps taken by (tyre manufacturers) Michelin over the winter."
Williams were runners up last year but won only the Malaysian Grand Prix.
Ferrari introduced their new F2002 after Ralf won that race and were immediately in a class of their own, winning 15 of the 17 races in a record-breaking season.
MORE AGGRESSIVE
Williams, winners of nine constructors' titles and seven drivers championships between 1980 and 1997, recognised afterwards that they would have to develop a more aggressive car to close the gap.
Technical director Patrick Head hoped they had done that: "The chassis derives little from previous cars," he said. "2002 showed us that our chassis was a model of reliability but that there's still room for improvement particularly on the aerodynamic front.
"That's why the FW25 is a completely new race car."
The new car is shorter than last year's and, despite limitations imposed by the regulations, has a new aerodynamic package.
BMW motorsport director Mario Theissen said the new P83 engine was designed to be, like last year's model, the most powerful engine in Formula One.
New rules have been introduced for 2003 with single-lap qualifying, a new points structure and the elimination of so-called electronic 'driver aids'.
Montoya qualified on pole seven times last year and Gerhard Berger, Theissen's co-director at BMW, said Williams were determined to pick up where they left off.
"But for the 2003 season we have firmly resolved to claim more wins and podium places," he said.
"We're focused ahead while also keeping an eye on the competition in the rear-view mirror."
The new car was due to run at the circuit on Friday afternoon before starting full testing on Saturday with Spaniard Marc Gene as official test driver.
