Help with playback speed

Ummm, hi, I just downloaded this .avi, and I play it with the latest versions of BS Play and ffdshow, and the image looks great and the audio too, but the problem is that the video goes more slowly than the audio, and its a concert video so its important , there are some configuration that i could change to make it play faster? My machins is a Celeron 400 Mhz with 96 MB RAM (8 of the 96 are shared to the SIS 620 video chip) and 4 GB HDD... I would buy a new video card... but for taht I need a new motherboard, and for that i need a new processor... and for that i need a new RAM... and a new HDD.

Thanks for reading this :D