The conventional wisdom has the Buffalo Bills choosing a defensive lineman, preferably an end, with their first-round draft choice. But the club is also looking hard at the cornerback spot. Always cognizant of what is upcoming for his team, general manager Tom Donahoe knows that current starting corner Antoine Winfield is eligible for unrestricted free agency after the 2003 campaign. And the feeling on the part of some Bills officials is that Winfield, given the spiraling rate of cornerback contracts, could be difficult to retain. Thus the interest in perhaps adding a quality corner in the draft and, quite possibly, even in the first round.