Converting bitmap line drawing to reasonable size GIF

I've got a few drawings that I want to convert to GIFs for my web page. The drawings were done with DrawingBoard LT (a wonderful little CAD program that suits my needs just fine, too bad it's not available any more). The native format is *.vlm which I believe is Ashlar Vellum. But I can export of *.WMF, DXF, or BMP (windows bitmap). So I export to BMP and get an 11 megabyte file. Then save as GIF using ACDSee - 28k. Looks good. No prob so far. We're talking about a line drawing with some text.
But the file is 2300 pixels high and wider that my screen. So I gotta shrink it to a more reasonable size. I have a bunch of photo editing software I have accumulated (legally) over the years. In addition to ACDSee, I have LViewPro, Corel Photo House, Adobe Photo Deluxe Business Edition, and the Microsoft PhotoEditor.
So, I try Corel. Turns the GIF to gibberish & can't read the BMP. ACDSee turns it into an unreadable grey-scale image, even though I specify Black & White in the "Image Properties". Adobe just crashes when I try loading the bitmap and also turns it into a grey scale image. I can't figure out LViewPro. Microsoft PhotoEditor also turns it into gibberish.
So, off to the Linux machine (Mandrake 9.1). Load the GIF in GIMP, but haven't got a clue on how to operate that software. Try to load it using the other software, but it seems it's all viewers, no editors.
Help! How can I turn those nice big line drawings into something usable on a web page?
Luigi Replace "nonet" with "yukonomics" for real email address
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