batchUpdate vs individual updates
===

Assume a table _TABLE_A  which contains  3 LATITUDE,LONGITUDE AND LOCATION.
   It contains around 10000 records . where LOCATION IS NULL. I need to find location using the LATITUDE AND LONGITUDE. LOCATION can be found using findLocation(lat,long) method.
Now this table is a live table which is used by around 200 users (select queries) 
and another person is updating around 20000 such records per min.
and I need to update this table also at the same time.

this is wat i have used for now. 
step 1:ResultSet rs =  select LATITUDE,LONGITUDE,LOCATION FROM _TABLE_A where LOCATION IS NULL
step 2: for every rs.next() , find the location then rs.updateString("LOCATION",location);

Its updating around 1400 records per minute. but my aim is to update around 20000 records per minute. And also i am not allowed to use multiple threads.

Please Guide.. 
my worries : first to attain 20000 records updation within a minute also should not effect Database.
I am using SQLServer 2005.