Purchase a TV tuner. This will allow you to run the cable into your computer and give you access to all the channels your TV receives. The TV tuner will come fully quipped with a program on how to set up your DVR.
Upgrade your media software. Windows Media Center is a great option, which is usually included with newer model PC. If you need it, an outright purchase of this software would be well worth the upgrade to produce a homegrown DVR.
Purchase an external hard drive. If your computer is so old that the hard drive cannot contain at least 40GB of data, then you can simply go out and purchase a large external hard drive. This will allow the large video bytes room to breathe on your computer and allow for flawless viewing.
Record while not using the computer. Unless you are using a brand-new computer which has a duel core processor, it is recommended you do nothing else while the DVR is running. This will make certain your favorite shows record seamlessly.
Use your new media center to set up your DVR to record your favorite shows. Your new tuner will have most of the basic features of any DVR. You might not get the TV schedule that is downloaded for you by TiVo, but you will be able to record your favorite shows. You will also have a calendar feature allowing you the opportunity to set recordings for the future.