Can't View avi, mpg

Please help. I have tried to figure out and downloaded stuff and I just can't view videos in avi, mpg. wmv is my default. I even have problems now with some jpg pictures. I have Windows XP. Thanks

umm you will have to get the codecs i believe..

Well for AVI's, MPG's , mp3's and more a very good free add on is www.winamp.com

As for the jpg's XP has the "windows picture and fax viewer it comes free with it. And works quite well also.