<strikethru>I was trying to be naughty and upload these PDFs to the forum, but they're pretty large, so for now we'll only be able to read them at the source, on Scribd. But at least we won't have to worry so much about lawyers swooping upon us if they're on another site.
</strikethru>
Edit (September 2013) : Newer, better quality PDFs are now being sold online through the OBS/Drivethru sites - as an affiliate of DTRPG - to whom I have sold my soul for a handful of dollars- I'm now obliged that to recommend those products as opposed to file-shared versions on Scribd (also they are too large to email which would also be very bad!) - The newer versions are better managed in terms of PDF compression and have selectable text. When we first started this thread Wizards were not selling any of the old TSR products.
On Scribd -to read online ...
Red Basic Set (1983)
http://www.scribd.com/doc/31976389/01-Basic-Red-SetBlue Expert Set (inc. X1:Isle of Dread)
http://www.scribd.com/doc/32031997/D-D-Boxed-Set-02-Expert-Rules-the-Isle-of-Dread-X1Green (teal ;) ) Companion Set
http://www.scribd.com/doc/32306344/03-Companion-Green-SetThe same user who uploaded these has posted a few modules from the same period.