I had an e-mail from"Yahoo-MSN stating that I had won a large sum of money. Is this legitimate?

It's highly unlikely that a company such as Yahoo would be giving away money. I would highly doubt this is authentic and it sounds like what is called a "phishing" email. If they are asking for any type of personal information or your bank information I would use extreme caution and just delete the email.

Hope that helps!

Always check the URL when you click a link. Don't go for phishing mails ar other scams. They only try to get software on your computer and you never win a dime.
Consider mail from a person you don't know as spam. Yahoo, Google and other providers, only will send mil to explain changes in their service. All other mails are to be considered as spam.
Don't come back in a few days, telling your computer acts strange, after you clicked a link.

No e-mail that states you won a lot of money is true, neither from Yahoo, from rich people, from foundations who want to send you a lot of money. They are spam or a means to gain access to your bank accounts.

ITS A SCAM BY A GROUP OF MOTHER ******* BEAWARE OF THIS EMAIL FRAUD
Lottery scam is a type of advance-fee fraud which begins with an
unexpected email notification that "You have won!" a large sum of
money in a lottery. The recipient of the message - the target of the
scam - is usually told to keep the notice secret, "due to a mix-up in
some of the names and numbers," and to contact a "claims agent." After
contacting the agent, the target of the scam will be asked to pay
"processing fees" or "transfer charges" so that the winnings can be
distributed, but will never receive any lottery payment.[1] Many email
lottery scams use the names of legitimate lottery organizations or
other legitimate corporations/companies, but this does not mean the
legitimate organizations are in any way involved with the scams.

There are several ways to recognize a fake lottery email:

Unless someone has bought a ticket, they cannot have won a prize.
There are no such things as "email" draws or any other lottery where
"no tickets were sold". This is simply another invention by the
scammer to make the victim believe that they have won.
The scammer will ask the victim to pay a fee before they can receive
their prize. It is illegal for a real lottery to charge any sort of
fee. It does not matter what they say this fee is for (courier
charges, bank charges, various imaginary certificates - these are all
made up by the scammer to get money out of their victim). All real
lotteries subtract any fee and tax from the prize.
Scam lottery emails will nearly always come from free email accounts
such as Yahoo!, Hotmail, Live, MSN, Gmail etc.

This nis spam mail donot reply to it. Even i get those mails.They are fake and you can see that they will be asking all your personal details which is dangerous to be shared so please avoid such mails. Just delete them off

It's a froud. Don't fall for it. It is a low process but it is risky for you, and I do not think it matters. If you have one that sum, I bet it wasn't just an email

this is nothing but trap! stay away from those mails!

I'm sorry, but this is a scam.

http://www.consumerfraudreporting.org/lotteryscam_Yahoo.php

Delete the email, and do not reply back or try to contact them.