preg_replace help

I have need to be able to replace text within a string to turn it into a link. In other words, I might have a phrase lik: "blah, blah, blah, please visit my site at www.mysite.com. blah, blah,blah". I need to have the string converted to "blah, blah, blah, please visit my site at http://www.mysite.com. blah, blah,blah". The link might have more than 3 sections and won't necessarily end in .com (.net,.com.nl, etc.). Here is what I have been testing (then I get stuck): $myLink = "Please visit my web site at www.mysite.com. You will be glad you did!"; $repLink = preg_replace("/(www.)/i","<a href=http://\\1",$myLink); which yields Please visit my web site at <a href=http://www.mysite.com. You will be glad you did! What I would need is Please visit my web site at <a href=http://www.mysite.com>www.mysite.com</a>. You will be glad you did! To be truthful, pattern matching is giving me migraines! Programming has always been natural to me (32 years of it), but this challenge (eregi, preg_match,etc.) is making me crazy! Can someone recommend a good tutorial or book on this subject? Thanks!