help with dvd playbak

hello and help
I have
dell dual xeon 1.7 workstation
ATI fire gl2 agp graphics card
1.5 gig ram
2×18 gig scsi
1×40 gig ide
MIAMIDI sound plus usb tascam us428
I cannot get video playback and am not sure about the drivers as far as I know I have the latest ATI
drivers for the fire gl2.
every dvd software player i have d/l’d says copy protection problems,one of the drivers [dvd or vga] doesn’t support the adaptors capabilities or hardware does not support copy protection. they give the advice to unplug the cables. that wouldn’t help much would it? unplugging the monitor?? HELP