Don't use Yahoo Messenger. Try using Trillian (http://www.majorgeeks.com/Trillian_d680.html
) instead. It does Yahoo, as well as AIM, MSN, IRC, and ICQ.
Oh, and you may want to ditch ME. Windows ME was a bad dream that got released to the public. You'd be better off with 98SE or XP if your comp can handle it.
Another thing to try... Firefox instead of IE. You'd still have to have IE to update Windows and a few (very few) sites that use ActiveX, but you'll find Firefox to be fast and very secure. Plus, there are likea thousand extensions you can choose from to add cool functions to Firefox. Here's a link to download Firefox: