Yep, Inkscape is a free open source replacement for Illustrator. It's not nearly so powerful, but it's got most of the features that 90% of users need. On the raster (Photoshop-like) side, there is the Gimp, which is quite powerful and even has a few features that Photoshop lacks.

Also, when saving out a version to post here on the forums, I recommend you use a more advanced file type than bmp. For vectory images with lots of flat colors, PNG is a good choice. For anything with texturing, use Jpeg. Bmp cannot be viewed in many browsers (including mine), so all I can see are the thumbnails. Plus, it's uncompressed, so the files are much larger than they need to be.