If it's a Dual 2.0, I'd go with the 2.0 for expandability reasons (up to 16 GB RAM vs. 4 GB, and multiple HDDs) ...and the fact that I just like PowerMacs better than "Mactels".
However, if it's a single 2.0, you might want to go with the 2007 iMac (assuming it's Dual core... I think all 2k7's had Dual core, right?).
If you absolutely need the latest video editing software all the time though, you might need the iMac, since as noted, Apple is likely to drop support for the PowerPC sooner or later... probably within the next three to four years, meaning you'll be stuck with the last OS that runs it (10.6? 10.7?), and whatever software was last available. Kind of like how 68K machines were no longer supported after 8.5 was introduced (Mac OS 8.1 being the last 68k-compatible OS), PPC604e's and earlier were dropped after OS 9.2 (workable with a hack, though...), and G3s were dropped with the introduction of Leopard 10.5.
It's your call, but it sounds like you'll be able to use the G5 just fine, assuming you aren't required to always use the latest software in 5 years.