The only thing I know is that Hungarian nationalists colleborated with the Nazis
What do you mean "collaborated"? After 1848 the jews grabbed most of the wealth in Hungary and poisoned us with liberalism, during the first world war they got rich selling the soldiers saw-dust bread and taking everything from the peasants in the name of the war - they were the ones portioning out the food. After the world war they created a Communist state in 1919 by promising the soldiers social justice and war against the dismemberment of our homeland, and they murdered and tortured civillians in the rear while young men were sent off to fight in the Hungarian Red Army (and they made sure to launch opertaions as bloody as possible to kill as many young Hungarian men as possible).
The Horthy regime which followed the Communist state sold out to them, was financed by rich jews, and did very little against them. Even after they comitted Communism they controlled the media, and were the rich in the Horthy regime - while the people were poor. They even got richer on World War Two. Virtually all of the weapons manufacturers during world war two were jewish (which is why a Hungarian bullet cost three times as much as a German bullet, and no effective Hungarian Tanks were ever built). Hungary was a refuge for jewish criminals up untill 1944 (nearly a million immigrated form Poland, Romania, and Slovakia) while the Horthy regime sent our soldiers to die in thin clothes, and substandard weapons (made mostly by jewish manufacturer, war profiteer and personal friend of Horthy - Weiss Manfred).
The Horthy regime entered the Second World War to avoid occupation by the Germans and shipping Horthy's friends off to Auschwitz (while they did everything they could to sabotage the war effort at home).
Finally in 1944 they were shipped off to detention camps, at that time the wealth of the Hungarian state fit in 16 railway cars, while the wealth confiscated from the Jews needed 19 railway cars.
I won't even go into what they did after the war, how they murdered children after 1956, or what they are doing today. If we did a few things to keep them from doing us more harm, and get a little bit of justice it wasn't because we don't like their religion, or "hate" them irrationally.
The Hungarian state was on the side of the axis to avoid invasion, Hungarian nationalists were on the same side as the Germans because we had the same enemies, because communism was a life or death threat, and because the Britain and France gave away 2/3 s of our country, and their governments have no sense of justice, honesty or decency.
As for the Serbs (you can ask the Bosnians about them - and they "love" Turks): they committed atrocities against Hungarian civillians during and after world war one, comitted crimes in the interwar period, Serbian partisans attacked Hungarian civillians during world war two.
In response a military police unit got a little rough with them.
The leader of the unit Colonel Zöld (Green) (if I recall correctly) had both his parents murdered by communists. The Horthy regime praised his actions at first, than a few months later the spineless bastards charged him with war crimes. The Serbs comitted more crimes after the war. Even today there are attacks against Hungarians in "Voivodina". That's the situation with the Serbs.