Yep, a Media Center PC would do, too, but youll spend a bit more expensive and you'd have to have internet access.
Typically the way these things work is based on a guide. I'm guessing all of them have the "Record 1:00p to 4:00p on Tuesday, 4th" function, but that is not the way these things are designed. They are designed to record Shows, not time slots.
The only non-subscription / non-rental option that is current is probably Windows Media Center. There are other things out there (DVD-recorders et al), but they seem to be randomly released...
I've used a number of different systems -- TimeWarner's DVR, DirecTV TiVo, TiVo Series 3, Windows Media Center, MythTV -- and I'd take TiVo for ease of use and stability any day of the week.