NYPost: Better watch Letterman tonight...

: "Any lingering doubts that David Letterman detests Bill O'Reilly will be laid to rest tonight, when the gap-toothed funnyman has the conservative Fox News powerhouse on his CBS 'Late Show' and machine-guns him with insults.

In a tape previewed by Page Six, things go downhill fast as O'Reilly sits down and jokingly presents the liberal-leaning host with a plastic sword to do battle and holds up a plastic shield to defend himself.

An irritated Letterman cracks, 'Oh, that's nice, that's cute, you come out with toys . . . Am I right about one thing: You guys over there at Fox and guys like Rush Limbaugh, you guys know it's all just a goof, right? You're just horsing around. You're doing it 'cause you know it'll be entertaining?' Letterman adds he's never seen O'Reilly's show because, 'I dial up Fox and it's always 'The Simpsons.' '

O'Reilly tries to lighten the mood by telling the audience he and Letterman are 'on the same bowling league' and asks whether he'd appear on 'Dancing With the Stars.'

'Bonehead!' snaps Letterman, who then starts shaking his fist and waving his arms at O'Reilly as the subject turns to the war in Iraq. 'Let me ask you a question - was there more heinous, more dangerous violence taking place [before America invaded] Iraq, or is there more heinous, dangerous violence taking place now in Iraq?'

'Oh, stop it,' O'Reilly scolds the host. 'Saddam Hussein slaughtered 300,000 to 400,000 people, all right, so knock it off . . . It isn't so black and white, Dave - it isn't, 'We're a bad country. Bush is an evil liar.' That's not true.'

'I didn't say he was an evil liar,' Letterman shoots back. 'You're putting words in my mouth, just the way you put artificial facts in your head!'"