Don't trust the internet to do your homework, kids.

I found myself on Answers.com today, poking around the Shakespeare questions.  The answers make you want to punch somebody. Let's look at the question, "How did Rosencrantz and Guildenstern die?"  Here's the answer that 3 people marked as useful:

Claudius sends Rosencrantz and Guildenstern to go back to England with Hamlet. Before the three of them leave Claudius sends a letter to England telling them to kill Hamlet once he steps on to their soil. The letter is to be delivered by Rosencratnz and Guildenstern, the both of them do not know what the letter says and are merely following the king's orders. It's important to note that Rosencratnz and Guildenstern are Hamlet's good friends and would not have delivered the letter if they had known it was in fact Hamlet's death sentence. Hamlet finds this letter and is convinced that Rosencratnz and Guildenstern were on Claudius' side and wanted him dead as well. In an act of madness Hamlet destroys the letter and rewrites a new one demanding that Rosencratnz and Guildenstern be killed when they step foot in England-no questions asked. He then seals the letter with a seal his father left him. 

Important things to look it and question would be : why is has the seal on him at all times and the sudden burst of irrational revenge towards two of his best friends.

Oy vey iz mir, where to begin?  They get the first part right, about the letter to England.  Then it takes a left turn:

It's important to note that Rosencratnz and Guildenstern are Hamlet's good friends and would not have delivered the letter if they had known it was in fact Hamlet's death sentence. 

Absolutely incorrect. R&G may have at one point been friends of Hamlet, but are now in the employ of the king. Hamlet knows this. He even at one point calls them, "my two schoolfellows, whom I will trust as I will adders fang'd."

It is a valid question to ask how they would have felt about Hamlet's upcoming execution if they knew the contents of the letter, but it is pure conjecture to state that they would not have delivered it. There's nothing in R&G's actions or words to suggest that they would go against Claudius' orders.

Hamlet finds this letter and is convinced that Rosencratnz and Guildenstern were on Claudius' side and wanted him dead as well.

Nope again. After opening the letter he never even mentions R&G. In fact it is Horatio who brings them up.

In an act of madness Hamlet destroys the letter and rewrites a new one demanding that Rosencratnz and Guildenstern be killed when they step foot in England-no questions asked.

Unless you consider the entire play one big fit of madness, I don't know where they get this stuff. In secret he forged a royal document, maintaining the original mission for the voyage. Remember that when he's doing this he doesn't realize he's going to have a chance to escape, he thinks he's going to be standing right next to them when the king of England opens the letter.

Important things to look it and question would be : why is has the seal on him at all times and the sudden burst of irrational revenge towards two of his best friends.

That he has the royal seal is just a plot contrivance of Shakespeare's, and not even a particularly unusual one. What's more interesting as an "important thing to question" is the sudden burst of irrational revenge toward two of his best friends. I'm not sure how many words in that sentence I can find to disagree with. Best friends? Nope, we've covered that. Sudden burst? Again, not hardly. They were on a sea voyage. He had plenty of time to think about it. Irrational? Changing the purpose of the mission and then planning to go through with the mission, that's irrational?  Irrational would be stabbing them in their sleep. Revenge? It's not revenge, it's self preservation. The entire purpose of this transaction is not Hamlet saying "Aha, at last I found a chance to kill Rosencrantz and Guildenstern!"  It's anything but. When Horatio awkwardly asks, "So, you just sent them off to their deaths, then, right?" Hamlet's only reaction is, "They are not near my conscience."

It's stuff like this that reminds me why I started Shakespeare Answers and Not By Shakespeare.