You must not "Newegg" often
! A grand for a high end sound card?!!! You can get the Asus Essence ST with the H6 add on card or the HT Omega Claro Halo for $250 or less. You can even get a Lynx or RME for 600 or less. Power supply, Enclosure, cooling and soundproofing - a computer builder could get all of this done for less that $1K if they got the Asus/Omega route. Gaming is another matter all together, but as far as high res video goes, most mid range video cards are already 4k capable. Software...$50 bucks for JRiver, XBMC is free and I can buy my O/S very cheaply because I'm in education. I talk like this because I've did it myself.
The issue is that this undertaking is not for the novice, nor is it for the person that doesn't want to take the time to set it up. Now once it's set - enjoyment - but if you're an A+ certified computer geek like myself, you will tinker with it. The good thing is that you will be your own support, you can fix it, upgrade it, whatever - all you want. While everyone else was spending $500+ on BD upon launch...I got in with less than $200 including software, just added the BD player to my PC and the software.
In fact, my first BD player was in my PC...almost 7 years later - I'm still using that same drive (I thought it had died - but it turned out to be a piece of memory). Ease of use? I control everything from my android phone - couldn't be easier. When something breaks - I'm not going to hunt down a repairman that's going to charge me a ton of dough because it's a highend piece of gear...nope, I'm going to remove the cover (if it's hardware) and replace what's wrong. If it's software I'll find a fix or see what offending piece of software has caused the problem. My PC has been my major source for years, and now it serves as my preamp and source - but I will say - I'm not the norm.
$5000?!!!! I don't see it. If I went all out with a build, with a ton of drive space (I can get 3TB drives for 99 bucks each). I could build a monster of a machine for less than half that amount - and what it would be able to do would be more than the prepro's that you've named. It appears to be a winning combination for a techie geek! (So this is what happens when you combine a PC geek with an AV lover - that's a dangerous combo
).