When I am trying to run tomcat using startup.bat
I get the following error,
The JAVA_HOME environment variable is not defined correctly
This env
I think that your JAVA_HOME should point to
C:\Program Files\Java\jdk1.6.0_25
instead of
C:\Program Files\Java\jdk1.6.0_25\bin
That is, without the bin folder.
UPDATE
That new error appears to me if I set the JAVA_HOME with the quotes, like you did. Are you using quotation marks? If so, remove them.