Those portable card reader hard drive combos are convenient, but those hard-rives are significantly less reliable than flash memory. I have a CF card that still works after a trip through the washing machine.
I think people often misrepresent the reliability of traditional hard drives. Compared to other computer components magnetic hard drives are the weakest link. With enough use all hard drives will eventually die. The probability that a hard drive will fail prematurely is actually pretty small, but personally I would still prefer the safety of flash media.
My only other suggestion would be to avoid keeping all of your eggs in one basket.
A prime is always a prime as long as its only divisors are 1 and itself.
Gear: Rebel XTI + Opteka Battery Grip | Canon 17-55 f/2.8 + Chinese Lense Hood | Canon 10-22 3.5-4.5 | 430EX | Lowepro Slingshot 200AW | LaCrosse BC-900 Battery Charger | Digipower card reader with Mood Light
Elan IIe + crap lenses