How do the Tivo and Replay TV units work? Do you have to subscribe to a service to use them or do you simply program them to record as you would with a VCR? Also, I'm interested in purchasing one or the other, but I'm not really sure what features are necessary, etc. (I'll probably only use it to record 10-15 hours per week) Any help would be appreciated.

For ReplayTV, the service subscription charge is built into the cost of the unit. Hence, ReplayTV's are a couple hundred dollars more expensive than TiVo's.

For Tivo, you can subscribe for $9.95/month, $99/year, or $200 for the lifetime of the recorder. I highly recommend the lifetime option if you go with TiVo.

The functionality of these units is greatly enhanced by the subscription service, and I would not recommend just using it as a glorified digital VCR without the service. It is so much more than that.

TiVo seems to have better market penetration than ReplayTV. TiVo also seems to be in better financial shape. Personally, I would recommend a TiVo over ReplayTV. Also, TiVo has a great community (and hacker community too) that you should visit:

http://www.avsforum.com/ubbcgitivo/Ultimate.cgi

Thanks!