In my time of doing seo I have read domain age can play a big role on how your site ranks in the search engines..My question is, if I picked up an expired domain will the se's still give me credit for the domain going back to 2003 or will it not get any "credit" for that?..Thanks in advance!
If the domain has expired long ago, the search engines most probably have dropped the rankings and any 'credits'.
Usually when you reregister an expired domain the date updates to current day. There are expensive backdoor deals done often for aged domains from registrars. You can also snap up some from some expiring services that will keep the registration date when you stick it in your account.