If you by on-line mean internet - then you can watch TV and have recordings set up and recorded without internet.
If you wan't to have a EPG Electronic Program Guide - then no need to fetch the TV guide regularly - I fetchs 14 days ahead each day - but yo can of course have a different interval and a different number of days ahead
Using DELL P4 1.5GB RAM 250 GB HD + DLINK DNS313 netdisk 1,5TB, 2 pieces of Hauppauge PVR150 w/45-button remote, 1 Popcorn Hour 110. Win XP SP3. GB-PVR v1.4.7 Plugins: Xrecord