Problems testing new map - GIMP DDS settings?

[Uggers]

Hi there!

I'm trying to create a new map (of the basic Freeport inn room, just so I learn how the process works), but I'm having problems testing it.

I've added the XML in _User_MapStyles.xml and I've copied the DDS file into the images/maps folder; however, after reloading the UI all I get in the mini-map is 'Map Unavailable'. I must have done something corrently because it no longer shows the 'Sorry!' message about no map having been created, but for some reason the map doesn't show up.

I have tried to follow the tutorial, but I don't have Photoshop so I've been using GIMP instead, with the following DDS plugin:
http://code.google.com/p/gimp-dds/
I wondered if I'd got the export settings wrong when saving my map image, because the settings in the GIMP DDS plugin don't match up with the Photoshop instructions in the tutorial.

Does anyone know what settings I should be using in the GIMP plugin?
Any other ideas about what might be going wrong?

Thanks!