In Windows XP, files and folders with numeric characters are sorted like:

Ie4_01                              Ie4_128                              Ie5                              Ie6                              Ie401sp2                              Ie501sp2
In Windows 2000, the same objects are sorted like:
Ie4_01                              Ie4_128                              Ie401sp2                              Ie5                              Ie501sp2                              Ie6
NOTE: When windows XP encounters a numeric string, it uses the numeric value as apposed to the string value. Numeric 401 is greater than numeric 6.

Accordingly, See the following sort order:

                              Windows XP        Windows 2000                                5.txt             11.txt                                  11.txt            5.txt                                88.txt            88.txt
You can modify the Windows XP SP1 or greater sort order to be the same as it was for Windows 2000, by running XPSortOrder.bat.

The syntax for using XPSortOrder.bat is:

XPSortOrder all         - To effect all users of the Windows XP computer.

XPSortOrder user     - To effect the currently logged on user.

XPSortOrder.bat contains:

@echo off                              setlocal                              If \{%1\}==\{\} goto syntax                              if /i "%1" EQU "user" set key=\[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\]&goto ok                              if /i "%1" EQU "all" set key=\[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\]&goto ok                              :syntax                              @echo Syntax: XPSortOrder all or XPSortOrder user                              endlocal                              goto :EOF                              :ok                              @echo REGEDIT4 >XPSortOrder.reg                              @echo.>>XPSortOrder.reg                              @echo %key%>>XPSortOrder.reg                              @echo "NoStrCmpLogical"=dword:00000001>>XPSortOrder.reg                              @echo.>>XPSortOrder.reg                              regedit /s XPSortOrder.reg                              del /q XPSortOrder.reg                              endlocal
NOTE: See How can I toggle the Windows XP SP1 treatment of numerical values in the sort sequence?