Why do i need a product key to use Microsoft word on windows vista?

Jaden, the product key proves that you own a legitimate, paid-for copy of MS Word. If you don't, or can't find the proof, I second the recommendation of OpenOffice as an acceptable and legal alternative.

If you had a product key and threw it out you're out of luck. If it was simply a trial version on your computer, you never had a permanent key anyway. As a student, however, you can get huge discounts on Microsoft software. Just get on their website and look for them.

If you had a legal copy of Word, or Office, then the product key came with that. If you "threw out all your computer stuff" then you may just be out of luck. Get OpenOffice, it's a free office suite with the same type of products that Microsoft office has, and it doesn't require a product key. Since you seem to be pretty helpless, I'll even give you the link! http://www.openoffice.org/

That sounds like a free trial copy of Microsoft Office that was good for 25 uses (of all Office programs combined) or 60 days. At the end of that time it stops letting you edit your files or create new ones. You have to purchase Microsoft Office 2010, or at least Word 2010, to do that. Note: The 25-character product key on the computer case or laptop bottom is NOT the key for MS Office. It’s only for the Windows operating system. Here are some of your options for legally paying less than full price for Microsoft Office 2010: First, if you're a student, you may qualify for the Office 2010 Professional Academic edition at a pretty good price ($79.95): http://www.microsoft.com/student/ Second, if you’re interested in buying just Word, check out this URL, especially the second group of listings. http://office.microsoft.com/en-us/buy/office-2010-pricing-information-HA101810737.aspx Also, if you have files that are locked up in the new Word 2010 file format (.docx), here’s a possibility for salvaging them. Microsoft offers a free Compatibility pack that allows earlier versions of Word (and Microsoft Works) to read and write Word 2010 files. If you have access to an earlier version, this can at least give you back your documents. Some new features of Word 2010 will be lost or converted to straight text in the conversion to the earlier version. Good luck.

Just google "open office" and install that instead, it does the same thing, and it's free.

Word is not included as part of Windows Vista (or any version of Windows.) Some computer come with a trial version that works for 30 days. After that you have to pay to keep it working. You do not get the code until you pay for it. Price is around $399. An alternative is go to http://openoffice.org and download a free clone of the Microsoft Office (which includes Word) called Open Office. Created several years ago for Linux user, it has recently been ported to work on Windows PC. It does everything that Word does, is even able to use all the Word file formats. Anything saved in Word format from Open Office is 100% identical to a Word document. But the program is free. Includes clones for Excel, Powerpoint and Access also.