How to convert AutoCAD 2011 .dwg files to AutoCAD 2008?

Agata, I assumed this was a file that was an email attachment, in which case it can't be opened and needs to be downsaved to an earlier version before the user can access the file.

The simplest method is that when are going to save the file choose the option "save as". A window appear on your screen. Then select the version of the file in which you want to save it. e.g, 2008.dwg.
That's all.

u can use Export file to IGS or AUTO cad 08 or open your file in AUTO cad MEP and export this to older version of cad software.

its easy...
1.PRESS RIGHT 'CLICK' @ MODEL TAB
2.GO TO OPTIONS
3.CLICK 'OPEN & SAVE'
4.FIND 'SAVE AS'
5.CLICK THE 'BOX'
6.THEN FIND THE LOWEST VERSION OF AUTOCAD 2000/LT2000 DRAWING (*.dwg)
7.PRESS 'OK'
8.THEN TRY TO SAVE YOUR LATEST DRAWING FILE..
THATS IT...DRAWING FILE IS READY TO BE OPENED @ AUTOCAD LOWER VERSIONS

try this kaspar http://www.cadforum.cz/cadforum_en/qaID.asp?tip=4706

Or e-mail me the file and i will see if i can open them in my autocad and re save them for you :)

Thanks Robert, got is saved. It's working :)

sorry I'm late to this one, however for future reference Autodesk's "TrueView" software is now a free download and will convert the most recent DWG's to a couple different prior years' versions.

Is this really necessary? I just choose the wanted version from the Save As pop-up window, under 'Files of type'..

Just "save as" in older version of cad.