Pilots cannot exercise the privileges of their PAPER pilot certificates after March 31, 2010. Certificates issued under 14 CFR Part 63 and 65 will expire March 31, 2013.
FAR 61.19(h) reads:
Duration of pilot certificates. Except for a temporary certificate issued under §61.17 or a student pilot certificate issued under paragraph (b) of this section, the holder of a paper pilot certificate issued under this part may not exercise the privileges of that certificate after March 31, 2010.
If you still have your Social Security Number as your certificate number you will have to change that before ordering a replacement plastic Pilot Certificate first. You will need to allow a few days for that change to be effective before ordering your new plastic Certificate.