Newly build PC, problems with videos

[Pass-By]

I have Windows XP Home Edition SP2 installed on my new box. I just build this PC and have a GeForce 6600 on an ASUS K8N board. Using an AMD Athlon XP 3600+, and every time I try to open a .wma file, .avi file, or any media file, the computer lags up. I open the taskmanager and see that the media program is using up 99% of cpu usage. What could be the cause of this? I can play games like Battlefield 2 and Counter-Strike:Source just fine on the PC, but when I attempt to watch a trailer either streaming it or downloading and trying to open, the file is never opened.

 

[Pass-By]

Also I have 3gigs of DDR PC3200 ram installed.

 

[KSoD]

Do you have all the codecs needed? How big are the files? The bigger the file the longer it takes to open no matter what RAM and that you have. Not easy for any machine to open a 2GB video.

 

[Osiris]

http://www.free-codecs.com/

http://www.bsplayer.org/

http://www.theorica.net/

http://www.divx-digest.com/software/