mine is a direct tv/tivo combo unit from phillips. it came w/ a 40gig hard drive & would record ~35 hrs of programming. i added a second 120gig to it & now it'll record ~145 hrs.
it records off the digital signal from the satellite & does EXCELLENT.
i am about to purchase the dazzle 80 thing to dump all the shit i got on it to my new desktop so i can put stuff on dvd & save it & delete it off the tivo & free up space to record more.
the stand-alone units should record from digital cable just as good & are just as easy to "hack" w/ an additional hard drive. you can also add NIC to them, so the get their updates via dsl or cable internet.
hit me up if you wnat links