According to Nielsen Online, 78% of adult online consumers in the U.S. made a purchase via the Web within the previous six months.

Travel-related transactions were most common, with 38% of adult online consumers making at least one travel purchase on the Web in the previous six months.

Large percentages of online consumers also went online to manage their credit card accounts (36%) and conduct personal banking transactions (35%).

Nielsen’s findings are based on data from @Plan, a quarterly survey of approximately 36,000 U.S. Internet users age 18 and older.

In October, eBay and Amazon were the top two online retailers, drawing 49.2 million and 48.3 million unique visitors, respectively.  Wal-Mart, Target, and Netflix rounded out the top five.

“The challenge for retailers is no longer how to lure shoppers online, but how to differentiate their brand among all others,” Nachi Lolla, research director, commerce, Nielsen Online, noted.  “Heading into this competitive holiday shopping season, selection, price, and customer service are the key areas in which retailers can shine.”

View the full press release.

Read coverage of Nielsen’s findings on Digital Media Wire and in Brandweek and BizReport.com.

Today, the likes of Netflix, Apple, Microsoft, Amazon, Veoh, and Hulu are betting it has.  Instead, they’re throwing their resources into developing a new video source: online streaming movies.

These new media titans may have the right idea, according to recent research by Nielsen that found online streaming video usage almost doubled in the U.S. between 2006 and 2007.  A separate survey conducted by Nielsen in 2007 found that 40% of respondents had streamed some type of video, while just over 10% had downloaded a full movie.

But while consumer generated media streaming has taken off online, movie content streaming accounts for only about 1% of all online streaming activity, according to Nielsen. 

But that trend may be changing fast, according to a new report by Nielsen PreView.  So far in 2008, movie content streaming has grown by leaps and bounds, outpacing the growth of streamed consumer generated media, the most popular streamed content, by a factor of eight.

Online video streamers are also an increasingly engaged lot, with more people streaming online movies for longer periods of time.  Between November 2007 and May 2008, those who streamed 30 minutes or more of online video grew by 4%, according to Nielsen. 

What’s trigging the growing popularity of online streaming video?  In part: broadcast TV content available for streaming online. 

Consumers who streamed more than 43 minutes of broadcast content during a recent seven-month period had the highest likelihood of being online movie content streamers, according to Nielsen’s report.

Read Nielsen PreView’s report.

Learn more about other recent Nielsen PreView studies on R-Ratings and 3-D films.