Just thought I would post this here for the benefit of other newbies.
I had difficulty with a book recently after not checking the retain my card details box, after winning I couldnt withdraw funds back to the card I deposited with because I didn't check this option. The only way they said I could do it was to upload more funds to the account, check the box, and then withdraw incurring more transaction fees.
As it happened there was a happy ending as it forced me to start using Moneybookers which I have found to be brilliant, so all good. However if this is standard practice on most books, then I'd like to share this experience because this was not something I came across in the sites T&C's and hasn't been mentioned once in the multitude of guides I read before getting into this.