The 30-year-old said: "I've been to a few quarter-finals but every time I thought we've got a chance of getting to Wembley, we have been knocked out.
"There were games where we were expected to win when we were drawn at home but it never happened for whatever reason.
"I was a YTS lad with Everton when they won the FA Cup in 1995. That was a good occasion at Wembley but it seems a million miles away now.
"I think this is the biggest club game of my career. We're getting close to having a chance of getting a trophy and it will be good to look back when I've retired and be able to say that I've won a medal and played at Wembley.
"But, because of my record, I don't even want to think about the possibility of a final. I know how difficult these two games are going to be.
"The opportunity is there but we have to make sure we're 100 per cent right for the two games and that we are still in contention going into the second leg."
Trophy success would also guarantee Villa a place in Europe, although their main target is a Champions League spot via the Premier League.
But Dunne added: "No one has mentioned the fact that winning this trophy would get us into Europe.
"The main thing is it is a chance to get a trophy under our belts, although there's still much work to be done."
Villa overcame Blackburn 3-1 in the FA Cup on Saturday but Dunne believes that will have little impact on Tuesday night's game.
He said: "There will be a lot of changes on both sides probably from Saturday and a different style of football.
"I think they will be a lot more direct with their approach on Tuesday and we know how difficult it is."
Villa boss Martin O'Neill said: "We are going to try and score a goal in the first leg, keep the game tight and still be in it for the second game.
"Winning on Saturday will not do us any harm psychologically but the style of football will be different.
"We will have to compete physically, and deal with set-pieces. We know what is coming and it is up to us to handle it.
"We played two-legged games in Europe last season and that experience shouldn't do us any harm. Every time you get the opportunity to play two legs, you should learn something from each occasion.
"If there is any advantage to be gained, it is because we have the second leg at home and if it goes into extra-time, away goals etc etc.
"But we have a lot of respect for Blackburn and we have to be on our game."
Winger James Milner is Villa's major selection worry after missing Saturday's game with a foot injury and he was only able to undertake light training today.
The likes of Dunne, Gabriel Agbonlahor and skipper Stiliyan Petrov will return against Rovers after being rested at the weekend.
Number two goalkeeper Brad Guzan is likely to again feature on Tuesday, after playing the majority of Villa's cup games this season ahead of fellow American Brad Friedel.
Blackburn v Aston Villa. Click here to bet.