Video Issues

I recently bought a Ge Force 6600 AGP video card, however I am experience issues I had never encountered before. One program I use everyday is a program called Poser 6. I can use this program with old drivers installed however I can not view any sort of movie format (ex. mpg, avi ect...) But when I updated my drivers I can view movies but I can not run this program.

This program is on a external hard drive, and I can not understand why it will not work with the updated drivers but work with the old drivers. Its like im sacrificing one program for another.

I have contacted Nvidia about this issue and they just tell me to pick a driver and use that driver they basically didn't want to help me solve this issue. Hopefully I can get the answers here.

My Computer specs
1400Mhz
Anthon
768 RAM
30 gig
160 gig external Hard Drive (which has my poser program on)