iMac/Mac mini vs. i7 PC

If you want to experience OS X, then go for an iMac i5 or i7 (note you can also run Windows on a Mac). If you want Windows 7 only, go for a i7 PC.

No doubt about it, you'll get more raw speed for a lower price on an i7 PC.
If you're going the Mac route, you have to be in it for the love of the software, not the hardware.

How serious are you about editing video? I know iMovie is great for beginners, but I've heard some complaining that it's too weak once you've got some experience. In that case, you might want to look at Final Cut Express.
Of course, you probably know a lot more about video editing software than I do, as I have done next to zero work in that area.

If you do anything that involves rendering, go for a i5 or i7 - don't buy Core2 anymore.
I just build a PC with an i5 750 2.66GHz and this machine is way faster then a Core2Duo 2.8GHz.
I did a test render of a scene in Maya, the i5 needs 2:45min and the Core2 needs 7:00min.

....and this is why I am holding off on buying myself a Mac Mini this year. I purchased one for my wife earlier this year (Mac Mini: 2.26Ghz + 4GB ram) as a 'testing the waters' for getting into the Mac world. We both love it and I want to jump aboard but I want to get a Core i5 or i7 for video encoding.

Sure, I could get an iMac now but I don't want my system and my monitor to be tied together...this is why the Mac Mini appeals to me so much. I am now anxiously holding out for next year's Mini refresh which I am hopeful will have either a Core i5 or i7 (fingers crossed) and not just a CPU+GPU speed bump. It is getting very hard though as my PC is an POS....another 6 months at the most I hope.