Most of the time, no. Nearly every tournament is played in standard style, which only allows the last two years of cards. This means that if you want to play competitively, then you need to buy new cards a lot. However, if you're just playing for fun, then it is fine to use old cards. There is a format called Expanded, which allows older expansions to be played. I don't know what the boundaries are on that but I don't think it will allow cards from 19995 or 1999.