I agree with Davin on using the keywords in the anchor text and switching them but:
Always use 2 links in your signature, one the way Davin explains and one without any html, just
http:// w w w yourlink . com
This is important because some article directories out there don't allow html in the signature line and if you only have a html link, then you will end up with no link at all.
You won't even notice that this happens if you are using an article submission software like the DigiXMAS tool or if you don't pre-view your articles.
Guido