Only if that content had already been encoded somewhere else. The Pentium 4 is simply too weak to recompress Hi-Def originals to a format which can be backed up onto BD-R (or more correctly, that P4 can do that, but it would take a lot longer than even the most die-hard video editor cares to wait for). And the Windows Vista/Windows 7 performance assessment tool (which gives Windows Experience Index scores for the individual components and overall), useless though it may be most of the time, is good for one thing: It does its best at showing just how well balanced the performance of a given system really is; in the case of my new i7 system, the hard drive performance is now the weakest point while on the 2.8 GHz Pentium 4 I am posting this from, the CPU is barely adequate to run the Windows Aero theme and with a noticeably lower score than everything else in the system).
As for the i7-920, it is a great chip. But be sure to get a newer chip with the D0 stepping since it can easily be overclocked to at least 3.6 GHz with stock cooling and stock voltages (even on the reference Intel DX58SO motherboard my particular 920/D0 is running on). The earlier C0 stepping needs a lot of help to achieve this high of an overclock.
By the way, I don't normally overclock my systems. Rather, I make minor tweaks to my systems in order to enhance stability (such as fixing the core voltage to the reference 1.2V as to not drop to levels that may become detrimentally low).