I am getting my very first ht set up in a mid-size 15' x 15' room.

I went to a local "appliance" store that has a decent ht section and got the following recommendation, which I thought sounded fine (this being my first system, I have really nothing to compare it to but my existing tv and the tv speakers):

Marantz 5600
KEF iQ3 and iQ6
Yamaha yst 225 sub
Infiniti in ceiling speakers for the surrounds
Marantz DV-4600 dvd and cc-4300 cd players

The quoted price for all of this was about $2,800 before installation and cabling and a seperate remote (harmony). I have been looking for while and have to say it is pretty tough with all the options available and the price ranges available (literally I could look forever), but for what I have been looking at (receivers from yamaha, integra, onkyo and speakers from b&w, energy and polk), this seems to be a solid set up for a reasonable price. Is there anything in the system above that you think I could do significantly better than for the price, or does anyone have particularly bad experience with anything listed? I would love your thoughts.

Seperately, I will probably get the new 42" samsung plasma, which looks great in the store. Anyone have thoughts on that also?