I believe you need to find an mpeg2 codec. It doesn't exist in the regular software and are in the Media Center pack with WMC and DVD drive software. So the good news is you do not have to buy the software you can still get it free. You might be able to just download some drivers from it rather than all of it.
Or if your want to try the internet. There are lots of freeware mpeg2 drivers. You might also have one if you have any video editing software program or DVD driver disks.