Thanks for the PPC idea, but with 3hr battery life, thats not so hot.
I'll still mention it to him nonetheless.
Like I say, PDF reading is no longer a requirement.
As for headphones, I suggested the Sony EX90s, because they sound good, and don't completely isolate.
They are sort of open. If I was in Iraq, I would in no way want sound isolation.
Their hybrid design is a in-ear/ear bud mix, which is comfortable to wear.
I'm not big on canal types nor ear buds, but the EX90s fit great.
Cord is long enough, durable storage case, no headband to interfere with helmet, at $80 don't break the bank.
And finally, their very low impedance (16 Ohms IIRC) makes em easy to drive.