On a win32 platform you need also the gtk libraries.
You can get them from:
ftp://lazarus.freepascal.org/lazarus/gtk-dlls.zip
or
http://user.sgic.fi/~tml/gimp/win32
Download the gtk+, glib, and extralibs DLLs from this site. Due to
constant changes in
these files we do not maintain direct links to the files.
Place the dlls in your \windows\system or \winnt\system32 dir
Marc