Eh, yeah, 4U is more or less a tower...but its actually a little less 'deep' than a standard tower is wide. which isnt a problem...unless you have a fan that only fits in your tower by virtue of an inch or so. hehe, with the 'support' bar removed from the case I linked, the stupid silent square is like, a millimeter from the top of the case. That was my only concern. Don't ask me why i have such a huge fan, I dont have the slightest clue; I think i bought it on a whim. (although, it is pretty quiet)

I considered just laying my towers on their side....but I have 7 machines, and 6 different cases. Eh. Their not uniform, and end up looking, i dunno, tacky, to me. Additionally, their all slightly different sizes and such. So i have this (silly) desire to get them into the same 'style' of case just for aesthetics. Coupled with the rack idea, 4u cases make sense.

That said, i bought one of those, it arrived, my hardware fit, and I like the case. The hard drive and cd rom bays are removable, theres plenty of slots for hard drives; and i don't really care about glowy spark lies anymore, so the black case with one green and one red light appeals to me. Eh, maybe i just buy crappy cases, but I've had waay too many cases where the hard drive and cd rom bays are not removable; its nice to have the option when installing things. Also, these things have a ton of hard drive bays, LOL. So, totally happy with the case. Also, I havent (yet) noticed the fans being loud yet. hmm. If i start hearing an overabundant of jets i'll be sure to check that first tho!

yeah, DIY rack out of wood is definitely an option. OTOH, i think constructing it out of metal like the deadly-computer guys did would look slightly snazzier. I need to price both options. Can always just buy the cases one at a time and stack them until I decide.

The cluster-in-an-ikea is totally insane. i imagine it must be a total PITA to work on tho. seems like you would have a hard time if say; the bottommost PSU died. Or a mobo in the center went bad. This is just me speculating from looking at what he did hehe. Tho it gives me ideas...maybe If i decide to 10box at some point in the future, and suddenly need 5-6 more cases, i'll try something similar. I used to think it would be cool to stick more than one computer (PSU, mobo, CPU, etc) inside a single box; but never could figure out a scheme that wouldn't be holy hell to service. Still, was a cool thing to look thru, am jealous tho...6 Quad cores, 8 gigs of ram each...seems like he put some serious money into that cluster.
Also, now im thinking it'd be cool to have my own cluster...mm. Something to do in the future when im bored, maybe.

never heard of a rack-mount flight cases; but i remember reading somewhere that musical equipment and computer racks use the same 19" specification, i take it tahts what you are talking about? (I know nothing about music or musical equipment.) hmm. oh well, time to Google =0