Very roughly average.
If you record to .ts (dreambox) it can depend on the bitrate & quality of the channel you record and how much action the program has. On average I find a standard 1.5hour movie will use average 2.2 gb but sometimes its only 1.7gb, sometimes its 3 ~which is only 1gb per 'half hour'.
Personally i wouldnt say 60gb = 60 hours ; more realistic would be allowing about 40 hours
I just checked my receiver and its showing 59.97gb still free and quoting approx 31 hours record time left, but i think thats a little under estimate.
just had a look and i've got a recording which is 45 mins and 1204mb so that would work out at 1.6gb per hour which is approx 37ish minutes per gig... i think