WRT Liverpool's success, it depends on two things. I'd back them to get to the final from here - should beat PSV and have a realistic chance of beating either Valencia or Chelsea.
I think that if they meet us in the final, we'll win, I'll always back us against the Scousers. If they meet any of the 3 other possible teams (a distinct possibility) Liverpool have a decent chance.
WRT United having the experience at the later stages, I agree we have a good chance of winning it but not due to experience - this side is very different from the Treble side, and is also not as good.
VDS is a very good 'keeper but he's not Schmeichel, and similarly Vidic and Rio are improving as a partnership but aren't Stam and Johnson. Neither Evra or Heinze are as good as Irwin either. On the wings, Giggs is having a good season but we aren't getting as much out of him as we did then, due to needing to rest him more, and Ronaldo is only playing as well as Beckham back in '99, as he was having an immense season. And Carrick isn't Keane either. And obviously we don't have as much firepower upfront - Cole, Yorke, Solskjaer and Sheringham > what we have now by some distance IMO.
Additionally, when we won it, we had a lucky run WRT injuries (though Keane and Scholes were suspended for the final tbf), whereas we are now picking up injuries at the wrong time.