Go to CPW shop, or your local 'network' shop, and ask them if they will flash it for you. Usually, they'll send it to a central place, and give you a free replacement while they do the upgrade for you.
I got mine updated yesterday! the new f/w 5.24 has much to be thankful for!!! its sorted my GPRS over Bluetooth issue and generally, much better... I've posted below the full details of the update...