Integrate 2-channel or go all 5 channel


I'm at a crossroad and could use some advice. I'm looking to integrate a 2-channel into my HT environment. I have ~ $4K to spend and cannot decide whether to drop all of it on a modest 5.1 pre/pro and amp combo and retire the receiver, or integrate a 2-channel into the mix. Would I get significantly better sound from a 2-channel setup integrated into my existing environment? If I went 2-channel, I think I could do it for about half my budget. Today, I'm leaning towards the 2-channel. My preferred amp would be a McCormack DNA ??. I'm looking for recommendations for a pre-amp. The requirements are, HT passthrough, and a remote. I have 2-way monitors and want to keep my sub in the 2-channel mix. Does anyone make a 2.1 pre-amp? I also need some way to set the frequency cutoff between to mains and the sub.
Based on the need to use my sub, next week I'll probably be leaning towards all 5 channel gear, amp there probably would be a Bryston.
There are a couple questions buried in the above diatribe. I sure could use some guidance.

Existing equip:
Yamaha RXV-995 receiver
Vienna Acoustics Haydn mains
Denon DVD-1600 DVD/CD/DVD-A player
M&K MX-150 sub.

My musical tastes are mainly rock & roll, if you think Pearl Jam, that should give you a good idea. and techno(house mainly).

Thanks in advance
snipes
If you are doing HT and it is of importance go with a multichannel system. There are many fine 5 channel amps out there which you would be very happy with. The Proceed Amp 5, CJ 5600, Rotel 1075 ect. All in a variety of prices and configurations to suit your taste. For 4000 you might be able to get a Proceed Avp and one of the other 5 channel amps. The Anthem combo might be good. However with HT you will not be satisfied with two channel. With regard to subs I would want to know room size before reccommending the second sub although I have one two sub setup that I love.
Ksales: For arguements sake, let's say I went with a Bryston 5.1 setup, Bryston 9st and Bryston SP1. I can pick up each for 2K used. I've heard many good things about the 9st and Bryston amps in general. The SP1 processor is supposedly based on their BP25 pre-amp. I've heard good things about this as well. At first blush, it seems I should get comparable 2-channel performance from this configuration as compared to a Bryston 2-channel rig. Assumption is the 2-channel rig would sound good. As for the second sub, well that isn't in the cards. My neighbor already comes over and complains about the bass...that's a sore subject with me right now. Being able to turn up my system loud is one of the main reasons I bought a house over a condo...
I'm curious about your thoughts on this scenario.
Snipes, do you plan on purchasing three more Haydns to round out your 5.1 setup or do you already have the center and surround speakers?
Gunbei: I have the Theatro center, pretty nice and some old Boston Acoustics dipoles for the surrounds. I'll eventually upgrade the rear speaks as $$ and a good reason permit. The current selection of DVD-A leaves alot to be desired, I still pick them up as they come out though.
I think the OutLaw ICBM (Integrated Controlled Bass Manager)will help, and it can perform bass management for your dvd-A. it just $250 only.