it's not bad once your library is through the gauntlet. now the occasional redbox DVD or whatever works. and I've owned my 27" iMac for about 3 years and a handful of months... never felt like putting windows on it. felt it would ruin my experience, maybe I'll see about putting 7 on there....
edit: are iflicks or lvi windows exclusives?
It sounds like you have a Mac, but you do all your video processing on a Windows machine? That's pretty much my setup. I used to use MetaX to do the tagging on the PC. However, after the processing, all my video files end up residing on my Mac. That makes it convenient to do the tagging on my Mac as a final step before they go in my library. I use Identify - another excellent, Mac only, metadata tagging app.
I just tried an experiment and ran Identify on files which are shared from my PC. It worked much faster than I expected. Apparently Identify doesn't need to read/write the entire file to do the tagging. So, running something like Identify on your Mac might be a painless way to do the tagging of the files on your PC.