Have you ever heard a Mini?
No?
There you go!
Personally I would not like to have a Pro in my living room. The Mini runs circles around it in means of noise. You can't hear that thing. Perfect for a HTPC!
Mac mini is quieter but it cant really handl 1080p mkv files very well. I had the mac mini 2.0GHz model and it did play hd movies fine via plex player but when I tried to run 1080p materials it had problems at some scenes where it would slow to a crawl in terms of fps.
I dunno. If he uses the HD154UI green drives which have a max operating temp of 65c and which typically run at 30c to 35c at Mac Pro factory set fan speeds then I guess he could just leave the fan speeds at factory and the Mac Pro is also completely silent. It'll run on the higher side of warm but it'll be silent.
starting to think that selling it and buying/build my own htpc is the way i might go. Just need to find a buyer!
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I have a guy that will give me $1500USD for my Mac Pro, should i do it, $1500 could get me a pretty good htpc build, no?
Pretty close. I think the $2k mark is more suitable for a "good" HTPC. But are you sure you want to? The Mac Pro does everything
you want to do except for the BRD
protected disk playback - and there may be a remedy for that in the near future(?). Also WinTel boxes need lots of care and consideration to make them quiet.
I notice people saying to use Mac Minis as a HTPC but that's pretty dumb IMO. It'll only work if you stay on Apple's prescribed path. Meaning no space for ripping, no BRD, no surround sound output - at least I don't see any (see image), no eSATA which means
slow I/O if you add storage to it for ripping, it's not upgradable or user serviceable, and like
jjahshik32 says it can't really handle 1080p very well, etc. etc.
Power, NIC, FW, 2 Disply, 5 USB, 2 Audio (line in/out, headphone)
So IMHO the Mac Mini is probably the worst choice there is. I seriously don't think there is a worse choice except maybe a laptop.

On the other hand if all they're doing is stereo DVD playback and XdiV internet downloads then it (or a laptop) will be just fine.
BTW, I recently added 5-1 surround processing to my Mac Pro 1,1 and wow what a huge and delightful difference there is from just stereo. And my stereo is a $2.5k audio kit so it's no slouch! And OMFG, when I put a DTS disk in and play it I'm emerged in a sea of sound. Of course my neighbors probably don't appreciate it as much as I do but what the hey - I'll just bake them some cookies or something.

Seriously the only downside to true surround is when there's a door-knock on my FR speaker (which is by my room-door) I say, "Who is it, come in", and when there's a telephone ring on my RL speaker (which is next to the room phone) I dunno if I should answer it or wait for an actor to get it.
EDIT:
Evidently the Mini's audio ports are "combined optical digital (minijack)" and can support 5-1 contrary to my assumptions. I had assumed all "minijacks" were only copper. Here's the low-down on 5-1: http://www.thismuchiknow.co.uk/?p=24 and here's the Mini's specs (see the bottom of the center column): http://www.apple.com/macmini/specs.html . So the other limitations I mentioned still apply but it seems there is actually 5-1 capability. 