If you want to import your points into SpatiaLite, it's easy to get the total number of employees in each buffer. Suppose we have a point table "firms" in spatialite with columns "firm_name" and "num_employees". Assuming you want buffers of size 5000, then
First create the buffer polygons table:
CREATE TABLE firm_buffers pk_uid INTEGER PRIMARY KEY AUTOINCREMENT,
firm_name TEXT, ttl_employees INTEGER;
SELECT AddGeometryColumn('firm_buffers','geometry',<your SRID>,'POLYGON','XY');
Now create the buffer polygons:
INSERT INTO firm_buffers (firm_name, geometry)
SELECT firm_name, ST_Buffer(geometry, 5000) FROM firms;
Now update the ttl_employees column:
UPDATE firm_buffers SET ttl_employees=(
SELECT SUM(f.num_employees) FROM firms AS f
WHERE ST_Contains(firm_buffer.geometry, f.geometry));
That should total up all employees from all firm locations with a buffer.