I install the bitcoin client on every computer I use (except for my work machines, which don't belong to me), and routinely transfer funds between them.  That way, I distribute my risk around multiple points of failure, so I can never lose my BTC.  And I always backup the wallets on each machine to both an external storage device and cloud storage, so if one or more machines die for any reason, I can restore the wallet to a different client.  Of course, all wallets are encrypted, so if any copy is stolen, the thief will find it worthless.