What do you think of my "water cooling" case design?

[3Z3VH]

I am not sure if this is something you plan to just build for yourself, or to have produced (as you have hinted at) but the majority of computers nowadays are moving toward having at least some sort of eSATA support. Replacing the Firewire port on the front with eSATA would be a very good move. I can not think of a single person I have met that has used Firewire400 in the past 2 years. If they have a Mac, they use the faster Firewire800 (1394b) now, which isn't compatible with the old 1394a connector, and isn't even present on current PC motherboards as far as I have seen.

Also, there is plenty of room above the hard drive cage, is there any way to put a bit more space between each drive to allow a bit more air through ?

One more thing... cable management. Be sure, when you lay out the standoffs on the motherboard tray to conform with ATX standards, that you cut a few large holes for cables to be run behind the motherboard tray, so the users won't have to do it themselves (and trust me, they will, if you don't

Otherwise, I think the case is a winner. I also vote for Aluminum, due to the weight, and ease of manufacture.

Edit: On the topic of fan sizes... perhaps designing a replacement face, or mounting plate with a different size fan mount would be better. This would allow buyers to upgrade to larger fans by buying the 140mm plate, or 200mm plate giving them the choice of which fans they wish to use.