Backing up wallet.dat

[BitMofo]

Is it ok to backup the wallet.dat file before the coins in the wallet are confirmed? Will the confirmations continue when the wallet is reloaded in the client? Or will they become lost?

[antares]

yes this is ok. Your wallet only represents a sort of private key to your addresses and those addresses themselves. with that private key your coins will be reassigned on a new bitcoin install when the blockchain is downloaded.

[FreeJAC]

yeah, all the transactions (bitcoin coming and going) for your wallet (unique address) are in the block chain. They exist regardless of the status of the wallet.