A few thoughts/reactions from grazing over your site.
Could use a little more mention of the benefits of quiet computing.
I realize that quiet computing isn't your main focus, but if you think in terms of the users local environment removing noise pollution is one way of improving it. If you are already going for low power consumption,
adding in low noise might not be too hard, then it could be another way of differentiating your systems from the rest. (A link to a quiet computing sight, like silentpcreview, or quiet computing wouldn't hurt
How come there isn't an option for Linux, or no OS?
(At least on the basic machine - I haven't looked at the others.)
If somebody is upgrading and already has a license for the OS they want, they may not want to be forced to get yet another copy of Windows.
Would help reduce resources used by not creating another OS disk
(not to mention saving on price.)
Similarly, an option for an open source office suite would be nice.
Carbon offset - why 1 ton? Is that a pitance compared to how much carbon will be generated to power this thing? Is it overkill?
Give some scale of comparison - How much is that in terms of KW-H, or how long you could run my system, or shipping weight? Would be more relevant if it were also given in terms of approx emissions from shipping the computer and/or how long can run computer for that amount of carbon. (Of course there would need to be a lot of assumptions/approximations in such a calculation, but your average person probably has no clue how much 1 ton of carbon is in terms of KW-Hours.)
Here is a chance to educate people about effects of power usage -
take advantage of it. (Even better would be if it would calculate power usage for the configuration I had selected, and give it to me in
watts, $ (use typical electricity rates, or let me plug in my rate) and carbon emissions. Let me see the cost of that fire breathing graphics card etc in total cost to run the beast.)
In terms of the longevity goal for your systems - do your cases have dust filters on the intakes? (Not clear from the description.) Though I don't have statistics on this, I would be surprised if dust was not one of the major causes of computer problems. (Fan failures, erratic operation due to overheating, etc.) If your cases do have filters, you might want to add cleaning the filters regularly to your list of general computer tips.
If not, might see if there is evidence that having periodic dusting increases computer life.
It would be nice if you had a few links about environmental computing (especially about the hazardous materials used in IC/PCB/ etc. fabrication, florescent tubes for LCDs, scanners, ...).
At least add a few good links so they don't have to hunt around to find out more about 80plus, RoHS. Even better if you can do a brief explanation of what nasties are used in computer manufacture, how yours are improved (and what could be done even better).
Also the printers could use better coverage in terms of what toxics (if any) are involved in ink/toner production.
It doesn't seem to indicate which computers/components are or aren't compliant with the RoHS directive. (Just saying incorporating components could be anything from one card to everything. Would be nicer to know which items are "greener".)
Strange that you don't seem to mention batteries.
For instance - the "help me decide" text for the cordless mouse/keyboard option makes no mention of the batteries that must be involved. If want to go green, should point out that a corded solution is greener, (doesn't involve heavy metals like Cadmium, etc. used in batteries, nor the extra materials and bother of making/recycling batteries and a battery charger, and more energy efficient (no losses in charging the batteries, then discharging them again, etc.))
Rather than just suggesting using rechargeable batteries, you could offer them (and a charger) as an option/accessory.
What about the laptop batteries - how green are Li-Ion batteries vs other sorts?
What sort of CMOS batteries are used (both in laptops and in desktops)? How green are they?
(Lest this sound too critical I think it is great that folks are taking on these problems, these are just the suggestions for improvement that struck me while browsing your site.)