You ever heard of a sure thing? You probably have because you are in MSFT. But for the record, BRK did not underperform (read their annual report at berkshirehathaway.com). I have held BRK for about the last ten years, and I have done extremely well.
No doubt I would have made more money had I put it all into MSFT, but a little diversification keeps you safe.
People slam WEB cause he won't invest in techs, but they can do that for themselves. GO MSFT & BRK - Happy investing !!