In order to check which version you must download, go to the source folder of your distribution (go to you distribution CD and browse the folders into the program files\Borland\Delphi7\Source\Rtl\Sys\ folder, or the corresponding directory on your running installation), and check the System.pas file date.
If the System.pas file month and year are 08/2002, download SynopseRTL082002.exe
If the System.pas file month and year are 09/2002, download SynopseRTL092002.exe
If the System.pas file month and year are 04/2004, you should have already applied the 7.1 update: try to download SynopseRTL042004.exe
You can download the compiled System.dcu and SysInit.dcu (for Delphi 7) from SynopseRTLdcu.zip
New! Patcher for Delphi 2007 System.pas and SysInit.pas is SynopseRTL2007.exe.