Check that DATE /T on your computer gives it in this format and with the number part in the form MM/DD/YYYY That's a requirement for the 2 FOR statements to work.
On my computer, DATE /T gives
C:\>DATE /T
Tue 11/15/2011
C:\>
Put a reference to the batch file in the task scheduler. you could run it once a month.. To test that the task scheduler is running it, I suggest moving your computer clock.. I've read that Task scheduler(possibly in XP) can be a bit funny with whether it executes batch files but test it.
Run this in task scheduler every month.
Contents of backup.bat for month\job format
FOR /F "TOKENS=1,2,3,4 DELIMS=/ " %%A IN ('DATE /T') DO @set mm=%%B
FOR /F "TOKENS=1,2,3,4 DELIMS=/ " %%A IN ('DATE /T') DO @set yyyy=%%D
xcopy c:\jobs c:\bkup\%yyyy%_%mm% /e /I
If you want it in job\month format, as you wrote, then firstly be aware that you given no place to put the files from c:\jobs you'd just be copying each subdirectory and its contents.
You only want this batch to run once a month, so put it in task scheduler.
For any of these xcopy lines that get run, if there is no file or subdirectory within the specified subdirectory of jobs, then no directory structure will be created, but that shouldn't matter.
Like if c:\jobs\a has no file and no directory in it. Then c:\bkup\a and c:\bkup\a\yyyy_mm will not be created. Which should be fine. Other jobs e.g. the job in subdirectory b, if there are any files or directories in it and there would be if you have any work there! it'd create the directories at the destination.
This may help you understand part of the backup.bat that follows
C:\>for /f %f in ('dir c:\jobs /ad/b') do @echo xcopy c:\jobs\%f c:\bkup\%f\%yyyy%_
%mm% /e /I
xcopy c:\jobs\a c:\bkup\a\2011_11 /e /I
xcopy c:\jobs\b c:\bkup\b\2011_11 /e /I
xcopy c:\jobs\c c:\bkup\c\2011_11 /e /I
Contents of backup.bat for backup in the job\month format.
FOR /F "TOKENS=1,2,3,4 DELIMS=/ " %%A IN ('DATE /T') DO @set mm=%%B
FOR /F "TOKENS=1,2,3,4 DELIMS=/ " %%A IN ('DATE /T') DO @set yyyy=%%D
for /f %f in ('dir c:\jobs /ad/b') do xcopy c:\jobs\%f c:\bkup\%f\%yyyy%_
%mm% /e /I