Reb Ahron Kotler told over the following story:
There was a man who donated large amounts of money every month to the Yeshiva of Volozhin. Reb Chaim, the Rosh Yeshiva, went to visit the man to thank him. The generous benefactor told him that he has no family and the only thing he wants in return is for someone to say kaddish and learn Mishnayos for him when he leaves this world. Reb Chaim assured him that he would do this personally.
Several years later this man died, and Reb Chaim attended the funeral which was on a very hot summer day. After returning home, Reb Chaim, remembering his promise, immediately starting learning Mishnayos for the neshama of this man. He was learning Seder Toharos and was having trouble understanding a Mishna. From his toiling to understand the Mishna and the heat, Reb Chaim fell asleep. While asleep, the recently deceased benefactor came to him in a dream and thanked him for learning Mishnayos for him and proceeded to fully explain the Mishna that Reb Chaim couldn't figure out. After this incident, Reb Chaim said that he always knew that one who supported Torah would get to learn and understand Torah in Olam Habah, but he never realized how fast this happens. The funeral was hours ago and this man was explaining one of the most difficult Mishnayos to one of the greatest Torah scholars of the generation.
After Reb Ahron Kotler finished the story, a student asked Reb Ahron why he leave the Yeshiva and support many Torah scholars and then he will know all that Torah in Olam Habah. Reb Ahron responded beautifully: "It is 100% accurate that you will know all that Torah in Olam Habah, but what kind of Olam Hazeh will you have without learning Torah.
(Similarly, Reb Elazar Shach was once speaking with one of the great supporters of Torah, and Rav Shach said that he is really not sure which one of them will get more reward in Olam Habah, but he said that he himself definitely has the better Olam Hazeh.)
Many people say that Reb Chaim Volozhiner's Nefesh HaChaim is the Litvish response to Chasidus and that the sefer proves that many thing said by the great Chassidish Rebbes are in error. Reb Gedaliah Kenig wrote a sefer, Chayei Nefesh, proving that this is incorrect and there is no argument between them, He says that he has kabala passed down that there is no argument between Chassidim and Misnagdim on the principles and foundations of Yidishkeit, as they are beyond dispute. Parts have been translated into English by Rabbis Dovid Sears and Dovid Zeitlin, of The Breslov Center , and are available for download (PDF) - Part 1 and Part 2. They are quite fascinating and explain a lot.
The yahrzeit of Reb Chaim of Volozhin is 14 Sivan - Zchuso Yogen Aleinu