Think this might be more what you're looking for :

declare @origstring varchar(50)

declare @strlength int

declare @teststr varchar(5)

declare @newstring varchar (50)

set @origstring = 'C:\Documents and Settings\file.xls'

set @strlength = len(@origstring)

set @teststr = ' '

while @teststr != '\'

begin

set @teststr = substring(@origstring,@strlength,1)

if @teststr != '\' set @strlength = @strlength -1

end

set @newstring = substring(@origstring,0,@strlength + 1)

select @newstring