So lets see now, more on my little $1300 i5 laptop.
4 day dive trip cut up into a 50 minute video.
Passengers given their DVDs as they walked off the boat.
Edited the raw HDV mts footage mixed in with raw Cannon 60D movs on the same timeline in real tine (Canon needed some rendering).
Colour correction, speed and titles required no render except with the Canon files.
On the last morning I rendered out from the 50 minute timeline both a PAL 720 / 576 and 720 /480 NTSC MPEG 2 DVD files with ac3 audio.
That took a total of 60 minutes :-)
The MPEG 2 files were dropped into a PAL DVD authoring program where I made even chapters for each dive then compiled the DVD ready for burning.
That took 10 minutes in total. 
I then did the same for the NTSC version which took another 10 minutes.
Then I just burnt the disks.
Then a customer wanted a ipod version so I rendered out one for her in under 30 minutes.
On the QUAD MAC using iMovie HD it takes over 3 hours to achieve the same thing before I can start even burning DVD,s and that is only for PAL.
Even more time if I need to make NTSC versions.
Plus all colour, speed and titles have to be rendered and all footage has to be transcoded before it can be edited not to mention it cannot even work with Canon files. 
Its a no brainer.....:-)