Not at all a bad system. I built a pretty zippy box back in November/December (as you may recall) and I'm still pretty impressed with how fast it is. It also came together for around $2,100 - but that's without the monitor, which I aleady had, and without a CD burner, which I have in my PowerMac.
Building a high-end computer is fun. Or at least it is for geeks like me. The design, planning, execution... and then using it and realizing that you do indeed now have a fast box... all fun things. I'm probably going to build a new computer in the fall and I've already started planning it. It's probably going to run Windows (which I find exceptionally difficult to do and usually end up installing Linux), so I can be more liberal in my hardware choices. I'm going to stick it in a Yeong Yang YY-0221 cube case most likely. The product page is at
http://www.yeongyang.com/products/yy0221.htm
and some pictures can be seen
here. I don't think it's going to be a $3,000 computer but it will definitely be pretty capable. Probably GF4 video, gig of RAM, one of the new Abit boards, 2 x 80 GB hard disk, PlexWriter, etc.
As for Macs vs PCs... Well, I used to hate Apple. One can only lie to oneself for so long.
The machines they're making now are top of the line, no doubt about it. I prefer using MacOS X over any other operating system now. It doesn't have all the conveniences of MacOS 9 (which definitely had a lot of conveniences), but it's still very functional. I haven't had it freeze/crash on me once. My iBook hasn't been rebooted/power-cycled in months. Macs are just a joy to use.
The Antec case you have in the picture (middle) is pretty nice. I have a Lian Li PC-12 for my main box but one of my other machines is residing in the Antec. It doesn't have all the super duper whizbang features of the Lian Li but for $65 or whatever they're going for now, it's a strong buy.
The case on the left... those are a dream to work with
No opinion on the other one