@DenverD:
mid-1990's definition:

Windows 95: n. 32 bit extensions and a graphical shell for a 16 bit
patch to an 8 bit operating system originally coded for a 4 bit
microprocessor, written by a 2 bit company, that can't stand 1 bit of
competition. <http://monster-island.org/tinashumor/humor/win2bit.html
and many other places...originating author?>

to get to 16 years later (today) not much is changed:

Windows 7: n. 64 bit rehash of 32 bit extensions and a graphical shell
for a 16 bit patch to an 8 bit operating system originally coded for a 4
bit microprocessor, written by a 2 bit company, that can't stand 1 bit
of competition.