My car makes a noise when it starts

I have a 2005 v-6 and when I first start my car, its makes a real high pitch whinning sound that will last for about 10 sec. before it starts to whine down.Then after that, its ok. It will not make any noise after that when I start it unless it sits for any lengh of time (6 to 8 hrs.) Can anyone Please tell me what might be the problem and If Its something I could fix myself?

If it is a loud sound, you probably need to replace the serpentine belt. You can do it yourself, but it may not be worth your time. Parts and labor should cost you around $100; doing it yourself might cost you a weekend if you have never attempted this replacement before. The belt is a very tight fit, and while the replacement can be done by one person, you might want to have someone to help you, who would just keep the tensioner pulley in it’s closest position to the engine.
If you do this yourself there should be a diagram on the inside of the hood to show you how to fit the belt onto the various pulleys. If it’s not there, refer to this site:
http://www.greatautohelp.com/How-To/Replace-Belt.html