go to the directory where oracle  is installed.
go to jdbc
go to lib

here ull find some zip file.

therel be two files - classes111.zip, nls_charset11.zip

or classes12.zip, nls_charset12.zip

if u find these files simply set the "classpath" variable in system
variables to these two files.

eg d:/oracle/jdbc/lib/classes111.zip
&
d:/oracle/jdbc/lib/nls_charset11.zip

if u dont find these files, take it from someone who has it.