Confused about LGPL terms - can you help?

[xp_newbie]

I read the LGPL terms here:
http://www.opensource.org/licenses/lgpl-license.php

I would like to use an LGPL library for a commercial (and not open
source) program I am writing.

I intend to use that library by *dynamically* linking to it (as a
Windows DLL). That is, the library will remain completely separate and
unmodified (the way I originally downloaded it).

Obviously, if I need to link to it, even dynamically, I need to place
#includes to key header files of that library (i.e. those that export
the functions prototypes and #defines) in a file of my own source code.

My question is: Under such circumstances, will I be obliged by the
license to make the source code of *my program* ( = "trade secret")
available to the customer?

If so, how is LPGL different from GPL?

Thanks,
Alex