Import the spreadsheet into an alternate, temporary?, table rather than you want to update and use an UPDATE statement with a where clause matching data between your Primary Key field in the table you're updating and the appropriate field in tha table holding the excel data.
Rhys
"There are some oddities in the perspective with which we see the world. The fact that we live at the bottom of a deep gravity well, on the surface of a gas-covered planet going around a nuclear fireball 90 million miles away and think this to be normal is obviously some indication of how skewed our perspective tends to be"
DOUGLAS AD