Hello,
Thank you for quick answer. Meanwhile I also successfully enabled Clean URLs on Drupal 6. I used IIS7 URL Rewrite module, and I imported rules from IIRF ISAPI Rewrite module (example for Drupal, which is included in the package).
After that, Clean URLs worked fine, but there was no CSS and no images. I noticed that if I enter full URL to CSS file, I get Sever Error, something about rewrite module. I just added another rule on the top of them all, so that if the wildcard *.* matches with entered URL (files), every mod rewrite rule isn't applied, and after that, Clean URLs are still working fine and also CSS and images are applied.
Best wishes,
Marko