Brendan Rodgers' Liverpool went from seventh to almost winning the title this season, when United ended up seventh.
Van Gaal signed a three-year deal with United, and Van der Sar believes Liverpool's efforts should give the Netherlands coach hope.
"It will be difficult to get from seventh to first, but Liverpool almost did it and I think United have more qualities than Liverpool on that score," he said.
"Van Gaal is going to be very clear about what he wants and what he demands from his players.
"It's great that Ryan Giggs is going to stay on as assistant coach so that Van Gaal has input from him and will know the feeling in the dressing room."
Van der Sar, who worked under Van Gaal with the Dutch national team, said the former Ajax and Barcelona coach was the experienced type United needed.
Van Gaal won multiple Eredivisie titles with Ajax and the 1994-95 UEFA Champions League, while he led Barcelona to two La Liga crowns and Bayern Munich to a Bundesliga win.
"Of course it's going to be a tricky period for him with the World Cup deciding on what transfers he will need, but if anyone can cope with a situation like this it is Van Gaal," Van der Sar said.
"His credentials in Spain, in Germany, in Holland with the national team speak for themselves. He has won the title in every country.
"He has a history of winning trophies, of bringing young players through, of working with big players.
"He is a very hard-working coach and he is a guy who makes players better. He also sends out the right signals about the kind of football he wants to play to the players."
