Did you know digital TV needs ~ 4.7GB of storage for either a 1/2 hour or 1 hour TV show? That's 1.3 billion bytes per second if I did the math right. Need some serious processing power for that.
Check this digital TV recorder - 500GB and 1 Terabyte hard drive. And I'm pretty sure it only records 1 or 2 channels as that is all the TV decodes at 1 time:
"*Recording function is undertaken by the TV, not the My Passport AV-TV. Refer to the TV's operating manual for recording options."
http://www.wdc.com/en/products/products.aspx?id=1250