Java EE (Java Enterprise Edition) General Discussion

My JDK is "1.5.0_04", download apache-tomcat-5.5.12.zip and expand it,then I start tomcat like follows:
C:\apache-tomcat-5.5.12\bin\startup.bat
Tomcat runs OK

But if I use follows command to start Tomcat,it raise error:
C:\apache-tomcat-5.5.12\bin\tomcat5.exe

[2005-10-19 22:33:27] [402 prunsrv.c] [error]
System can't find assigned file
[2005-10-19 22:33:27] [1246 prunsrv.c] [error]
Load configuration failed

If I use follows command to start Tomcat,it raise follow error:
C:\apache-tomcat-5.5.12\bin\tomcat5.exe

Unable to open the service 'tomcat5'
C:\apache-tomcat-5.5.12\bin\tomcat5w.exe

Why I can't use tomcat5.exe or tomcat5w.exe to start Tomcat? How to make Tomcat to start?
Any idea will be appreciated!