I used Corel Photopaint 9 for this.
First off I increased the general contrast of the image using the Sample/Target balance tool, then used the Level Equalisation tool to increase it a bit more.
Next up I used Local Equalisation in the Image>Adjust menu to achieve a 'painterly' look.
Local Equalization enhances the contrast near image edges and reveals details in both light and dark regions. It works a bit like the Auto Levels; however, instead of using the entire image to construct the histogram, only neighboring pixels are used. I hope it's not considered a filter as such. Either way I rather liked the result so I thought I'd better post it.