I've been using CountryHawk for almost a year now and have been very pleased with its accuracy and performance for my needs.  I had previously evaluated some free geotargeting software I found via searching the 'net, but I was not impressed with the results, and there was still a charge for updated data files.  With CountryHawk, I receive monthly updates which require one step to apply to my server (and which can be configured to occur automatically if you prefer), and these updates are included in the cost of my subscription, making the cost comparable to the "free" options I had considered.

CountryHawk is not a complicated product to set up and use.  It is very well designed, in that it does basically one thing, and does it very well.  If you need to know where your web site's visitors are coming from, this is the tool you should use.