GIMP Image Size Limits

Hello,

Are there any known, inherent, limitations on the size of images that may be
loaded and processed by the GIMP?

So far, I have loaded and manipulated grayscale images up to several hundred
megapixels, and that seems to work ok except for a few relatively minor
zooming bugs.  However, I've had some problems where my largest images (on
the order of 400 to 600 megapixels) have failed to open.  So far I have
chalked that up to hitting the wall on the available RAM on my machine
(presently 768MB).  Therefore, I am considering upgrading my system RAM to
1.5GB.  However, I would like to be certain that GIMP will actually be able
to work with these larger images if I buy the additional RAM.  I have just
learned that some other graphics programs that I've been using (ImageMagick
for example) have an upper limit on maximum image size of around 400M pixels
(2GB / 5 bytes per pixel), and I'm hoping that isn't true of the GIMP.  I'm
running extremely low on options for dealing with these images at the
moment.

Thanks.

s/KAM