The normal card whould work just fine.
Concerning the change of the card, maybe it's your browser cache that doesn't change because I haven't had that issue after generating a new custom card... the whole custom card upload process has been thought so that as soon as the new card is generated, the new background is used, and the previous, deleted.
Please tell me if there's anything else I can help out with.
EDIT : Thank you for the link in your current signature space, it's very nice of you.
...are so cool! Thanks. I have to find a customised pictures to upload.