Index: tomcat/trunk/res/tomcat.nsi
===================================================================
--- tomcat/trunk/res/tomcat.nsi	(revision 1378005)
+++ tomcat/trunk/res/tomcat.nsi	(working copy)
@@ -51,6 +51,7 @@
 Var TomcatMenuEntriesEnable
 Var TomcatShortcutAllUsers
 Var TomcatServiceName
+Var TomcatServiceNameAllreadyInstalled
 Var TomcatServiceDefaultName
 Var TomcatServiceFileName
 Var TomcatServiceManagerFileName
@@ -573,6 +574,15 @@
     Goto exit
   ${EndIf}
 
+  ReadRegStr $TomcatServiceNameAllreadyInstalled HKLM "SYSTEM\CurrentControlSet\Services\$TomcatServiceName" \
+    "DisplayName"
+  ${If} $TomcatServiceNameAllreadyInstalled != ""
+    MessageBox MB_ICONEXCLAMATION|MB_OK 'A service with the given Service Name is allready installed on the machine. \
+      Please choose another Service Name'
+    Abort "Config not right"
+    Goto exit
+  ${EndIf}
+
   Push $TomcatServiceName
   Call validateServiceName
   Pop $0