Want to edit HD video, Build recommendations please.

Hi,

I haven't done a new build in about 10 years...I make computers last....and my budget.

Anyway, I have lots of HD video that I took with a Canon HD Camcorder.

I'm a Linux user (an ancient core2 hand me down desktop), but I have recently moved to a Macbook Air and really like it.
It has been a positive experience and I'm a little torn from a OS perspective. Plus I can get to the command line.

Linux = Choice. Mac = Easy (and lots of 3rd party software)

So I looked on Apple's site and saw iMacs and Mac Pros. Both seem nice.
It might be an easy buy and I know everything will work. The built in software is nice and I am guaranteed that my Macbook Air and other iDevices will work fine together as its the same ecosystem.
I don't know if I can master a HD Bluray. Also I didn't see an option with a Bluray burner. I don't know why.

On the other hand, I know I can build a machine for much less, but would still need to purchase additional software to edit video. Also test everything, and make sure its all stable.

On the linux side of things, video editing when I had a mini-dv camera was painful to say the least. Windows has lots of software, but honestly, I'm not a big fan of Win7 and Win8 looks weird. And when I compare Win7 to my Mac, it looks like a bloated pig. (Sorry, I'm not a fanboi of either, but it just seems like things always go wrong with anybody that is running Win7, I am the tech-support person for my family so...)

I'm really looking for a recommendation. I want something powerful, that I can edit HD video in realtime. It doesn't have to render in realtime, but like move calipers and stuff to cut-n-paste.

(Playing steam games would be a most excellent bonus)

A mac pro starts at $2500 for a Quad Core Xeon @ 3.2 GHz.
A mac mini starts at $899 for a Quad Core i7 @ 2.6 GHz.

Or should I build something, and what can I build for $2500.00.

Thanks,

btanoue.\