Sounds somewhat newish …
Lots of faq' s on Ubuntu/Alfresco …
Windows … blah blah …. not a fan … Ubuntu runs great in a virtualized environment. Currently I have a KVM (kernel Virtual machine) setup with 4 vm's running - 1 server is running fog (cloning) the other is running alfresco in a dev environment, 1 Ubuntu workstation, and 1 xp workstation
If you're a tinkerer and looking to kill some time and sweat alot … go with slackware Ha! …
But if budget isn't a constraint … grab a dell 810 box with 4 cpu's and say 16gig of ram and then run 12 vm's on it …
there's alot of questions you have to ask yourself before you can truly answer this question …
How many users are you going to be having access alfresco at each location? Do you truly require multiple nodes? or can you just create a local cluster with a high avail failover setup?
anyways i'm rambling now
pz
m/soop