If your boss asks you to do something, and it's a quick task (not a major project), do it right away. For example, if your boss asks you to find out approximately how many PCs use the old version of Windows, get back to him with a decent estimate in a few minutes.
It helps to understand the big picture. Usually such requests are made because your boss is putting together a much larger plan or budget and you can hold up your boss's entire day by not getting back to him with an answer quickly. Perhaps he is working out the staffing and cost estimates to bring all PCs up to the latest release of Windows. The entire project would be held up while waiting for your answer.
Why does this matter? Well, your boss decides your next salary review. Do I need to say more?
Maybe I do. Your boss will have a fixed amount of money he can dole out for all raises. If he gives more to Moe, then Larry is going to get less. When your boss is looking at the list of people in the team, do you want him to look at your name and think, "He sure did get me an estimate of the number of out-of-date Windows quickly. Gosh, he always gets me the things I need quickly." Or, do you want your boss to be thinking, "You know, the entire budget was held up for a day because I was waiting for that statistic." Or worse yet, "All the times I looked foolish in front of my boss because of a missed deadline, it was because I was waiting for so-and-so to get me a piece of information. So-and-so isn't getting ...