How would you start with 5K?

Your approach is pretty close to the advice I give friends when they ask how to start down this path - put your money into two good fronts and a matching center, but a decent A/V receiver (Denon is my choice as well, but certainly not the only one), use anything you can scrounge up for the rears and buy a cheap DVD player. An alternative to this is to buy something lower in the line for the fronts and then move them to the rear when buying upgraded fronts from higher in the same line, but assuming $5K is all you're planning to spend in the next year or so you might find it too long to wait.

By the way - you got a comment about the 3801 where I think the writer was referring to the 5800, a much higher-end model from Denon. The 3801 is an excellent choice given your goals.

This setup would give you really nice performance initially and, depending on your desire and means to upgrade in the future, you'd have lots of options. First, depending on what you put in the rears initially, a decent set of rears could be had for $300 or less, new. Something from PSB or Boston Acoustics. BA makes a really nice dipole that is ceiling or wall mounted for about $400, but if you move a lot you might not want something that mounts. In another year you'll be able to get a sub-$500 progressive scan, DVDA DVD player which will be an improvement over whatever you get now for a couple hundred. Then, of course, you can replace the Denon with separates - if it has pre-outs, you can start with the amp and then ultimately the processor. I went from the old AVR-3600 to separates and the improvement was great. Throughout all of this, your L/C/R will give you a lot of enjoyment, and by the time you're done with these upgrades, you can decide whether these are your fronts for life or not. You're definitely on the right track - hope you enjoy it.

Charles - I think the 3801 is not intended to be that expensive - I had heard more around a grand. The 4800 retails for $2000, so I doubt they'll bring out another model at the same price point. In any case, Denon's whole lineup is really nice, IMO - pick your price point and buy the Denon closest to it and you'll probably be pretty satisfied. And I completely agree with the point you were making about the 5800 - if you dive into this by buying the 5800 you're probably making a big mistake if you're planning to upgrade it within a year or two - that's a seriously nice piece of gear and you should get years of good service out of it. If you're constrained by budget (and who isn't) and you're going the receiver route until funds build back up, buy a lower-end one so you don't take such a huge hit. As always, having a longer term strategy to guide your buying decisions will make it cheaper in the long run.