The typical U.S. computer in April was home to an average of 880 MP3 audio files, which took up about 3 Gbytes of storage space, according to a new survey out Thursday.

It also contained 197 Microsoft Word files, 100 PDF files, 77 Microsoft Excel files, and 36 Windows Media files.

These figures came from Internet metrics firm comScore, which is expanding its data gathering beyond the Web with a new service called comScore Tech Metrix. The company aims to help client companies improve their product planning and marketing by providing detailed technology profiles based on the 2 million people monitored by its tracking software.

ComScore's data also shows that U.S. computers are gaining storage capacity. The percentage of computers with hard drives of at least 70 Gbytes rose from 33% in January to 39% in April. During the same time, computers with hard drives of less than 50 Gbytes declined from 59% to 53%.

Linda Boland Abraham, executive VP at comScore, said comScore Tech Metrix represented the firm's first foray into non-Web based measurement. "When combined with Web behavior profiles, Tech Metrix data will help marketers develop a granular perspective of the machine configuration and behavior of key customer segments, along with how and where to reach them on the Web," she said.

As an example of the type of behavioral profiling comScore can provide, the company offered a comparison of sites visited by heavy MP3 users and average Internet users.

Heavy MP3 users, defined as the top half of PC users with most MP3 files, visit certain types of Web sites at a far greater rate than average Internet users. In April, heavy MP3 users accounted for 39.4% of visitors to gaming sites while average Internet users accounted for 19.4% of visitors.

This pattern repeats itself across other Web site categories, including online gambling, teen community, humor, music retail, and technology news sites. What use might this be? Well, an organization like the Recording Industry Association of America might see this data and conclude that heavy MP3 users represent the sort of customers that should be courted.

Another example is comScore's comparison of heavy Microsoft Word users to average Internet users. Word fans exhibit more interest in business, finance, and travel sites than those less fond of Microsoft's word processing software. They're also more interested in religion, accounting for 15.3% of those visiting religious sites in April, compared with 11.3% among typical Internet users.