The League One side secured one of the results of the fourth round, progressing to the last 16 and securing a home tie against Barnsley after they won 4-2 at Loftus Road on Saturday.
Former Leeds, Manchester United and Newcastle man Smith was the most experienced player in the Dons side and one of few with any Premier League experience.
The 32-year-old, a former England international, has also tasted Champions League football and was part of the Leeds side that beat both Milan and drew with Barcelona during the 2000/01 season.
Asked if it was silly to compare the Dons' win to such results, he said: "Not when you are coming to the end of your career. You remember them all.
"This one will be remembered as fondly as some of those results. Obviously it was not as spectacular as who you were playing against - they were all European giants.
"But it is a Premier League team who have spent a lot of money and we came and played good football. It is not as though we were backs to the wall and a 1-0 victory. It proved how good we can be.
"But the main focus has to be the league. The main thing has to be picking ourselves up for the game on Tuesday against Yeovil. That's reality. That's the one you have to be motivated for.
"These games are easy to get up for. These ones you are free to go out and express yourself. But the bread and butter is getting out of League One.
"That is proving difficult because there are so many good teams in there. We proved we are one of them."