Hi, struggling here with Excels datenumber...

I have as source the following table:

2006 2007
Jan 10 12
Feb 8 9
Mar 9 11
etc...


As a destination I have a report stating the following:

Jan-07 12
Jan-06 10

Whereby my report uses the Microsoftdatenumber as a reference
throughout, where Jan-07 is 39083 with the use of Format Cells Date
...
This value will change according to the month we live in :-)

Now the problem is: how can I use this datenumber to look up the
according value in the crosstable?
Normally I use INDEX() or VLOOKUP for this.
However, if I try to get "Jan" as a lookupvalue, e.g. through (LEFT();
3), this obviously does not return "Jan" but "390".
Is there I way to do this, pref. without adding an extra, intermediate
worksheet?

Important backgroundinfo:
My sourcefile is not made the way I would have it, but due to
"userfriendlyness" (i.e. the user-skill-level) I cannot change that.

Hope my question is at least understandable ^^

Thanx in advance for any help!