generating a new wallet for every transaction is a bit wasteful, you can however just create a new payment address, and watch for payments on that.
if you create a few hundred receiving addresses, then you can keep the wallet (and hence private key) offline, as all transactions are public, and minimise the risk of having funds stolen (as we've seen a lot of places lately getting hacked and having their accounts drained..)
if you create a few hundred receiving addresses, then you can keep the wallet (and hence private key) offline, as all transactions are public, and minimise the risk of having funds stolen (as we've seen a lot of places lately getting hacked and having their accounts drained..)