Must be member for X days before can vote on polls?

[WreckRman2]

I started a contest on my site wouldn't you know it I am seeing new members signup then vote on a poll. I'd like to set up a way to stop this and the simplest way would be to require a member to be registered for X amount of days before they can vote on a poll. This way if I run a poll for 7 days I can set it to not allow new members to vote until they have been a member for 8 days.

Anyone know how this can be done?

Thanks in advance!