Well with the Mobile 2500 he should get a brisk OC even in the SN45G and I'd think that the ability to haul your box to a LAN would be a nice consideration, not to mention the coolness that a Shuttle cube gives your whole life
Personally I'd get the cube
Yes, since my bro doesn't use his computer a lot (web browsing, mword, music, movies, bit of gamin) I don't really need a comp that overclocks. (NOt that I wouldn't overclock that M2500+)
I was thinking something cool looking and unique
looking would be nice.
I'm thinking of getting one for my GF too, after I experiment with the one for my bro.