A study by Nielsen/NetRatings released on Monday shows that most search engine users tend to use a second site to complete their searches. However, depending on which search engine the person uses first, sometimes a second search isn't necessary.

58 percent of Google users use a second search engine, the lowest of the top three search engines, while 70 percent of MSN users and 71 percent of Yahoo users turn to another of the top three.

"While it shouldn't surprise anyone that Google is the search engine to beat, it is critical that all of the major search players, including Google, recognize that they exclusively own only a minority of their users," Ken Cassar, director of strategic analysis for Nielsen/NetRatings said.

Google was the popular second choice of both MSN and Yahoo, with 33 and 39 percent of users respectively. About a quarter of MSN users used both, and 21 percent of Yahoo traffic went to both sites.

Also measured was the share of search query volume, or the amount of queries for external information on a particular site. Google led the pack with nearly half of all searches, followed by Yahoo at 21 percent and 13 percent for MSN Search. Altogether, out of 60 search engines surveyed, the top three garnered over 80 percent of all Web searches.

"With more share than its two nearest competitors combined, Google sets the pace in the search business," said Cassar. "However, the opportunities that MSN and Yahoo! enjoy by virtue of their broader media offerings give them an important platform from which to attack the industry leader."