A bit ugly but this seems to work. It uses the DOS ren command:
REN drive:\folder\filename.ext newfilename.ext
NB: The above is from WinXP
Not tested on Win98 but I think you need
REN drive:\folder\filename.ext newfilename.ext
oldfilename$="temp.txt" newfilename$="BlitzPower!!.txt" q$=Chr$(34) ExecFile "cmd /c ren "+q$+CurrentDir$()+oldfilename$+q$+" "+q$+newfilename$+q$ If FileType(newfilename$) Print "Renamed!" a$=Input$("Done ..") End
NB: The above is from WinXP
Not tested on Win98 but I think you need
ExecFile "command /c ren "+q$+CurrentDir$()+oldfilename$+q$+" "+q$+newfilename$+q$