--- a/browser/installer/windows/nsis/installer.nsi
+++ b/browser/installer/windows/nsis/installer.nsi
@@ -434,24 +434,18 @@ Section "-Application" APP_IDX
   ; If the maintenance service page was not displayed then 
   ; InstallMaintenanceService will be equal to "".
   ${If} $InstallMaintenanceService == ""
     Call IsUserAdmin
     Pop $R0
     ${If} $R0 == "true"
     ; Only proceed if we have HKLM write access
     ${AndIf} $TmpVal == "HKLM"
-      ; On Windows < XP SP3 we do not install the maintenance service.
-      ${If} ${IsWinXP}
-      ${AndIf} ${AtMostServicePack} 2
-        StrCpy $InstallMaintenanceService "0"
-      ${Else}
-        ; The user is an admin, so we should default to installing the service.
-        StrCpy $InstallMaintenanceService "1"
-      ${EndIf}
+      ; The user is an admin, so we should default to installing the service.
+      StrCpy $InstallMaintenanceService "1"
     ${Else}
       ; The user is not admin, so we can't install the service.
       StrCpy $InstallMaintenanceService "0"
     ${EndIf}
   ${EndIf}
 
   ${If} $InstallMaintenanceService == "1"
     ; The user wants to install the maintenance service, so execute
@@ -952,22 +946,16 @@ Function preComponents
   ; If the service already exists, don't show this page
   ServicesHelper::IsInstalled "MozillaMaintenance"
   Pop $R9
   ${If} $R9 == 1
     ; The service already exists so don't show this page.
     Abort
   ${EndIf}
 
-  ; On Windows < XP SP3 we do not install the maintenance service.
-  ${If} ${IsWinXP}
-  ${AndIf} ${AtMostServicePack} 2
-    Abort
-  ${EndIf}
-
   ; Don't show the custom components page if the
   ; user is not an admin
   Call IsUserAdmin
   Pop $R9
   ${If} $R9 != "true"
     Abort
   ${EndIf}
 

--- a/browser/installer/windows/nsis/shared.nsh
+++ b/browser/installer/windows/nsis/shared.nsh
@@ -126,18 +126,16 @@
   RmDir /r /REBOOTOK "$INSTDIR\${TO_BE_DELETED}"
 
 !ifdef MOZ_MAINTENANCE_SERVICE
   Call IsUserAdmin
   Pop $R0
   ${If} $R0 == "true"
   ; Only proceed if we have HKLM write access
   ${AndIf} $TmpVal == "HKLM"
-  ; On Windows 2000 we do not install the maintenance service.
-  ${AndIf} ${AtLeastWinXP}
     ; We check to see if the maintenance service install was already attempted.
     ; Since the Maintenance service can be installed either x86 or x64,
     ; always use the 64-bit registry for checking if an attempt was made.
     ${If} ${RunningX64}
       SetRegView 64
     ${EndIf}
     ReadRegDWORD $5 HKLM "Software\Mozilla\MaintenanceService" "Attempted"
     ClearErrors

--- a/browser/installer/windows/nsis/stub.nsi
+++ b/browser/installer/windows/nsis/stub.nsi
@@ -1040,24 +1040,16 @@ Function createOptions
   ${NSD_Check} $CheckboxSendPing
 
 !ifdef MOZ_MAINTENANCE_SERVICE
   StrCpy $CheckboxInstallMaintSvc "0"
   ; We can only install the maintenance service if the user is an admin.
   Call IsUserAdmin
   Pop $0
 
-  ; Only show the maintenance service checkbox if we're on XP SP3 or higher;
-  ;  we don't ever want to install it on XP without at least SP3 installed.
-  ${If} $0 == "true"
-  ${AndIf} ${IsWinXP}
-  ${AndIf} ${AtMostServicePack} 2
-    StrCpy $0 "false"
-  ${EndIf}
-
   ${If} $0 == "true"
     ; Only show the maintenance service checkbox if we have write access to HKLM
     DeleteRegValue HKLM "Software\Mozilla" "${BrandShortName}InstallerTest"
     ClearErrors
     WriteRegStr HKLM "Software\Mozilla" "${BrandShortName}InstallerTest" \
                      "Write Test"
     ${IfNot} ${Errors}
       DeleteRegValue HKLM "Software\Mozilla" "${BrandShortName}InstallerTest"

--- a/toolkit/mozapps/installer/windows/nsis/common.nsh
+++ b/toolkit/mozapps/installer/windows/nsis/common.nsh
@@ -1445,33 +1445,31 @@
 !macroend
 
 
 ################################################################################
 # Macros for handling DLL registration
 
 !macro RegisterDLL DLL
 
-  ; The x64 regsvr32.exe registers x86 DLL's properly on Windows Vista and above
-  ; (not on Windows XP http://support.microsoft.com/kb/282747) so just use it
+  ; The x64 regsvr32.exe registers x86 DLL's properly so just use it
   ; when installing on an x64 systems even when installing an x86 application.
   ${If} ${RunningX64}
     ${DisableX64FSRedirection}
     ExecWait '"$SYSDIR\regsvr32.exe" /s "${DLL}"'
     ${EnableX64FSRedirection}
   ${Else}
     RegDLL "${DLL}"
   ${EndIf}
 
 !macroend
 
 !macro UnregisterDLL DLL
 
-  ; The x64 regsvr32.exe registers x86 DLL's properly on Windows Vista and above
-  ; (not on Windows XP http://support.microsoft.com/kb/282747) so just use it
+  ; The x64 regsvr32.exe registers x86 DLL's properly so just use it
   ; when installing on an x64 systems even when installing an x86 application.
   ${If} ${RunningX64}
     ${DisableX64FSRedirection}
     ExecWait '"$SYSDIR\regsvr32.exe" /s /u "${DLL}"'
     ${EnableX64FSRedirection}
   ${Else}
     UnRegDLL "${DLL}"
   ${EndIf}
@@ -5952,23 +5950,17 @@
       ${WriteLogSeparator}
 
       ${LogHeader} "Installation Details"
       ${LogMsg} "Install Dir: $INSTDIR"
       ${LogMsg} "Locale     : $R7"
       ${LogMsg} "App Version: $R8"
       ${LogMsg} "GRE Version: $R9"
 
-      ${If} ${IsWinXP}
-        ${LogMsg} "OS Name    : Windows XP"
-      ${ElseIf} ${IsWin2003}
-        ${LogMsg} "OS Name    : Windows 2003"
-      ${ElseIf} ${IsWinVista}
-        ${LogMsg} "OS Name    : Windows Vista"
-      ${ElseIf} ${IsWin7}
+      ${If} ${IsWin7}
         ${LogMsg} "OS Name    : Windows 7"
       ${ElseIf} ${IsWin8}
         ${LogMsg} "OS Name    : Windows 8"
       ${ElseIf} ${IsWin8.1}
         ${LogMsg} "OS Name    : Windows 8.1"
       ${ElseIf} ${IsWin10}
         ${LogMsg} "OS Name    : Windows 10"
       ${ElseIf} ${AtLeastWin10}