Continual uptime while loading data ... COPY vs INSERTS within a transaction.

Hello,

We are running a system which requires continual uptime while loading 
data.  Currently one particular table receives a large number of inserts 
per commit (about 10000 inserts).  This process works well allowing both 
end users to access the data as well as loading reasonably quickly.

We are thinking of modifying our system to use COPY to replace these 
large INSERT transactions but we are concerned that it will greatly 
impact the user experience (i.e., exclusively lock the table during the 
copy process).  First, does COPY grab an exclusive lock? Second, is 
there a better way to load data?

Benjamin