Does a trademark certificate only protect a mark that is "famous" or does it protect all registered marks? What do you do if someone is infringing on your mark and will not decist because he claims that your mark is not "famous" and therefore, not protected?

You are right. The courts have determined that that famous marks are entitled to better or greater federal protection rights over that of non-famous aka lesser known trademarks. If you review the case law, there is not set definitive characteristics that define what makes a trademark famous.

The Federal Trademark Dilution does not define the term "famous". This is left for the courts to determine. That being said, most tests used to determine whether a mark is famous are subjective and verdicts will likely be inconsistent across circuit courts. However, there are some general guidelines under the Federal Trademark Dilution Act that courts consider and determining whether a trademark is famous:

1. How long has the trademark been used;
2. How long has the owner of the trademark been advertising and promoting the trademark;
3. Where has the trademark been used;
4. How distinctive is the mark (either through the nature of the mark itself, or through acquired distinctiveness);
5. What is the general degree of recognition of the trademark;
6. Are multiple third parties using the trademark
7. Is the mark is federally registered with the USPTO?