you can grab a video converter at your local big box electronics stores for less than $50. You connect the video from the dvr to the converter and it will send the video to your PC via USB or Firewire. Usually in some MPEG format. The more you spend the more options you get. some of the newer multimedia PCs have direct video input jacks, but I'm guessing yours doesn't.
I use my camcorder as it has a AV--> DV converter and I capture the video on my PC, convert it to Divx, and watch on my DVD player.