My PC cant play HD video...???

[Patriot]

i have intel 2.4GHz, 845 board, 512 ram, 160GB ide hdd, wth Winxp SP2 installed. whenever i try to play any HD video whether its 720p or 1080p, it opens in media player classic suddenly goes to full screen and the sound plays for 5-10 sec and im left wth a blank screen frm which i cant seem to get out without restarting, nothing works.
plz dont tell me to install codecs or VLC player or any player.. i've got it all.
So how do i play HD video?? or do i need a new PC??

[skippednote]

Just pop in an basic GFX card and u will be able to play all the video's cause i had same Mobo and it wasn't able to run HD videoz as it has less integrated GFX.