I have previously documented:

How do I disable the Windows XP balloon tips?

How can I disable some Start Menu Balloon tips?

How do I suppress the Windows Tour prompt in Windows XP?

How do I configure the 'Highlight newly installed programs' option via the Windows XP registry?

Here are a few more:

                              To disable Start button balloon tips:                                    REG ADD "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced" /V StartButtonBalloonTip /T REG_DWORD /F /D 0                              To disable folder content information bubbles:                                  REG ADD "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced" /V FolderContentsInfoTip /T REG_DWORD /F /D 0                              To disable popup descriptions for icons and folders:                                  REG ADD "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced" /V ShowInfoTip /T REG_DWORD /F /D 0                              To disable reminder balloons above the Offline Files icon in the notification area:                                  REG ADD "HKCU\Software\Policies\Microsoft\Windows\NetCache" /V NoReminders /T REG_DWORD /F /D 1                              To disable the reminder to apply for a Microsoft Passport:                                  REG ADD "HKCU\Software\Microsoft\MessengerService" /V PassportBalloon /T REG_BINARY /F /D 0a000000