I am including several links that explain what Event Viewer is and how it can be used. Useful information can be gleaned from the logs, but in typical fashion they don't make it easy for the everyday user to interpret.
Take a look at these and see if they help.

http://ask-leo.com/what_is_the_event...ld_i_care.html

http://www.windowsnetworking.com/j_helmig/wxpevent.htm

http://support.microsoft.com/default...308427&sd=tech

http://support.microsoft.com/default...302542&sd=tech

Don't be intimidated if the articles are for Windows NT or Windows 2000. Event Viewer for those is the same as in XP.