Sorry for the re-post, subject line was wrong.

In columns A & B, I have a list of dates and values, such as:

1/1/1998 12.7
3/10/1998 10.4
7/24/1998 14.6
8/3/1998 7.2
8/17/1998 42.4
12/10/1998 3.3
2/20/1999 12.7


Is there a formula that, upon entering a date, will look up the value
corresponding to the next date in the list (if there's no exact match)?
For example, if I enter 3/24/1998 in, say, cell D1, the formula would
return 14.6. If I can't get the value, can I at least use INDEX to get
the location of the next date?