Figured this out today and it works fantastically.
I have no idea what font is being used for the logo in Artemis but I wanted to use my own font anyway.
I also wanted it to look kinda cool and not plain.
Here's what to do.
1. Open logo_bg.gif in PhotoshopCS.
2. Create a new image with these parameters.
Background Contents: Transparent
3. Copy then entire logo_bg.gif image into your new transparent image.
(It should show up as a new layer.)
4. Stretch the layer left to right so that it covers the entire transparent image.
5. Now add your text and any cool layer properties you want.
(It's a good idea to anti alias your text to something like Strong)
6. Select File and Save For Web.
7. Save the image as logo.gif and upload it to the images directory in Artemis.
Now it should look nice and centered and the text won't be all strange looking.