@Bluefront: I hadn't seen that project of yours yet, but thank you for showing it here.
You know, it's not easy to keep track of your many projects.
This very design is in part inspired by your projects, so keep up the good work!
About the positive pressure issue: I doubt this kind of design would be able to cool PSU, HDDs, GPU and CPU with a single fan with positive pressure.
And putting the fan(s) on the bottom would have further increased the height of the design, which is already 5 cm taller than the NSK3480.
@DG: this setup should be able to cool a 8800GT with AC S1, but you are right that the CPU (passively cooled) would get toasty.
For a system with E8400 & 8800GT, at stock clocks, the maximum power would be around 160W, which would result in 25W of heat from an 85% efficient PSU.
But since the airflow would be directed straight towards the S1, better than in a P150 for example, it should cool it adequately.
For a HTPC using a BE2400 on the new 780 (integrated graphics) based uATX mobo, this design should work not just 'ok', but great.
You'd only need to duct the Ninja (or HR-01) to the fan, because Skt AM2 CPU positions are further away from the fan than Skt 775.
@Shaman: of course a front sliding filter can be well built, but who can guarantee that whoever would manufacture this concept will do it right?
Remember the issues with the P180 door?

Hinting at Antec as a possible manufacturer of this design.