Home Automation and the New House

So... the new house is nearing completion, and it's time to start thinking about how to outfit it. As this is a brand new home and we've installed a structured wiring plan, we want to deck it out with an audio/video distribution system and home automation system. Cost, however, is a huge concern, because, frankly... I don't want to spend a ton of money on new components or expensive hardware and systems that may be obsolete in a couple of years. Besides, I like doing this stuff, and I'd like to make it as DIY as possible. So... how do I do it?

Below are a listing of and the specifications for each part of the wired house.

Specifications

1. MultiZone A/V distribution
1. Dual Home Theater
2. Central location for all hardware
3. Any source in any zone capability
2. Home Automation (future)
1. Zoned lighting control
2. Thermostat control/monitoring
3. Irrigation control

Main Concerns

1. Low initial cost - pre-built, custom solutions can quickly and easily run into the several thousands of dollars. I don't have the money for that. I'm willing to sacrifice a bit of the "professional" look to get a workable, custom, expandable solution.
2. Upgradable - We don't have a lot of really high end stuff. We're not big into HDTV yet, and we just don't have the hardware. But that doesn't mean we won't WANT it. I want the ability to upgrade as we go without replacing the entire system.
3. Expandable - We want to be able to add components for media and home control as needed.
4. Central - I want to be able to control media, irrigation, lights, etc. from a limited number of control panels strategically placed around the house.
5. Mobile - if possible, I'd like to be able to use modile devices (PDA, cell phone, the Internet, etc.) to remotely control features while outside of the home.
6. Looks Nice - While I don't need the "professional" look of a Crestron or AMX system, I'd like the system to look nice and act more or less reliably.

Current Components for the Media System

1. Denon multi-zone receiver
2. DirecTV/Tivo - Series 1
3. DirecTV/Tivo - Series 2
4. Sony DVD Player
5. Sony CD - 5 disc carousel
6. Sony VCR
7. Sony Tape player
8. Windows XP-based media server/HTPC

Subsequent posts will detail the installation of the system.