Lets put things in perspective here regarding technology here.
It is true that the Byzantines and Muslim realms were generally technologically more advanced than Western Europe at the time of the First Crusade. Both cultural spheres produced remarkable intellectual achievements, and had well developed commerce. They also had more centralized administrations, could more efficiently levy taxes, and raise larger armies. By contrast, Western Europe developed a martial nobility, who received land and serfs in exchange for services to their lords. The wealth of these realms were heavily invested in to the weapons, armor, and training of this martial class. Therefore, Western Europe had a very small, yet elite group of full-time soldiers. It should be noted that this social organization was most prevalent in France and the Holy Roman Empire, and a martial nobility in some areas like Anglo-Saxon England were less important. Moreover, the French and Holy Roman Empire still conscripted peasants in to their armies, but emphasis in battle was placed on the knights.
In the 1000s, Western Europe experienced rapid population growth. By the time of the First Crusade in 1096, the economy was unable to keep up with population growth. This did not just affect the peasantry. Because of primogeniture, many nobles who were not first or second sons were unable to earn a living to sustain the aristocratic way of life they felt entitled to. Many of these knights subsequently turned to terrorizing the population, and the First Crusade provided a win-win solution for the disenfranchised nobility and the political elite. The disenfranchised nobility was provided an opportunity to enrich themselves, and the political elite got rid of them. They not only got rid of the disenfranchised nobility, but a lot of the peasants who went with them too.
Another key piece of information here is the characteristics common to the nobles that went on the First Crusade. They were disenfranchised sons, and many of them turned to crime. Though the European nobility was unsophisticated compared to their Muslims and Byzantine counterparts, the nobles who participated in the First Crusade in particular were even less so. The nobles who enjoyed higher status and had no incentive to participate in the crusade at least had some grasp of politics, strategy, and personal restraint.
Though both the Byzantines and Muslims employed heavy infantry and cavalry in their armies, both army organizations, especially the Muslims armies, centered on light troops. First, the Muslim realms were situated in a geography with a considerable amount of open spaces. Secondly, the Middle East had limited iron reserves, which would have had to be acquired in areas such Anatolia, Africa, Europe or India. As such, a reliance on mobile, light troops were typically more appropriate for Muslim armies. And since they had a developed system of commerce and a large population, they could afford larger armies.
By contrast with the military organization of Muslim states, heavy weaponry and armor were more abundant and practical in Europe. Though heavy weapons and armor were extremely expensive in Europe, the natural reserves of iron and economic/social organization of Western Europe enabled the small martial nobility to afford them. No, they were not 15th century knights equipped in full plate armor, but the equipment and training of 11th-12th century knights ranked them as among the most elite combatants in the world at the time.
In the First Crusade, there were a lot of disenfranchised knights who were eager to participate in the crusade. Thus, the crusader army consisted of a large number of heavily armed infantry and cavalry. Though many of them could not afford a horse or the best equipment, as a whole they were better equipped than their Muslim counterparts. With their better equipment and ability to launch heavy cavalry strikes, they inflicted heavy defeats on Muslim armies. In fact, the knight's equipment forced the Muslims to later adapt their armies to include more heavy troops specifically to fight the crusader states. Moreover, Muslim armies later learned to avoid confronting a large force of crusader knights, and instead harass them. Many times, the hotheadedness of the knights caused them to expose themselves as easier targets from the harassment provided by the lighter armed Muslims.
In battle, crusader knights were very effective against Muslim armies. The failure of the knights to maintain control of the crusader states was due to their own failings in diplomacy, tactics and strategy. Sorry, but sending your whole army in to the desert to chase Saladin without sufficient water provisions is beyond stupid. Not only did they error in that example, but their errors were so numerous it is a miracle they survived as long as they did and were as effective as they were. Not only that, but they betrayed their own Byzantine allies. They looted the Empire's territory when marching through it, back stabbed the Empire's army by deciding they wanted to monopolize the credit for conquering Egypt, and at one time they invaded the Byzantine territory of Cyprus, plundered its wealth, and imprisoned members of the Emperor's family who governed it! In short, they were typically more interested in their petty squabbles, personal glory, and personal wealth that they failed to consider the long-term consequences of their actions enough to spell their own ruin. Had they been disciplined and willing to cooperate with the Byzantines and their other allies, history in the Middle East would have turned out very differently.