I usually delete after watching, (except for a few classic movies) but right now I have over 600Gig of programs just waiting to be seen, and plenty more downloading daily.
Probably different for others, but I don't have the luxury of renting many English language movies here... Very limited selection. As for TV in English, the choices are even fewer! With open source torrents I have the choice of about 36,000+ English language movies and about half that of TV shows... entire seasons of shows!
Ain't THAT the truth!! These torrents keep my security systems hopping, both for virus, spy-ware, and mal-ware, and all three are running real-time. But I notice that 99% of the troubles come from software, especially those with key-gen files. Never had any problems with movies or TV programs. and so far (touch wood) my security has caught everything that has tried to enter my system. It pays to use the very best if you're going to play with other people's files! That, and have all my data files backed up and stored separately. If a virus does get in, a quick re-format, install, and reload, and I'm back in business in 4-5 hours. No big deal with nothing lost but time.
Using external storage memory means that I can keep my tower case internal temperature cooler, which is a big plus in tropic heat. If I added two more hard drives to my tower set-up (I do have the room,) I'd want to add a liquid cooled cooler system to protect my CPU, and the good ones of those cost a couple of hundred too! My external drive cases all have cooling fans and temperature monitors in them but so far even when room temps are in the high 30's C for days on end, everything has stayed cool enough so as not to worry about overheating.
Stitchawl