The worldwide Internet ad market will be an exciting place for the next few years, according to a new report from IDC.  By the time 2011 rolls around, online advertising still won’t have replaced traditional methods, but a whole lot more money will be involved than what we see today.

Online advertising is expected to be a major subject when advertisers from around the globe meet in Cannes on the French Riviera as the industry tries to deal with uncertain economic times.

About 12,000 ad people, art directors, markets, producers and clients will attend the week -long Cannes Lions 2008 festival that started on June 15 and runs to June 21.

Revenue from U.S. online advertising increased by 23.9 percent to $7.1 billion in the first quarter compared to $5.7 billion in the first quarter of last year, according to IDC.

Despite the sluggish economy, IDC expects Internet advertising to continue to expand rapidly during 2008, even though advertising across all media will most likely be cut back as advertisers look to save money and find more effective marketing channels.

Global PC shipments grew by 14.6 percent to 69.5 million units in the first quarter of 2008, which beat previous estimates of 13.2 percent according to IDC’s Worldwide Quarterly PC Tracker.

The U.S. market showed signs of the economic slowdown, but growth remained positive at 3.5 percent for the quarter. The other international markets compensated for the U.S. coming in more than 2 points above estimates due to continued strength in developing countries.

Internet users are spending more time online than they are spending watching TV according to a new study by IDC.

The study found that Internet users spent 32.7 hours per week online and about half as much time watching television (16.4 hours). Time spent reading newspapers or magazines accounted for 3.9 hours per week, while overall time spent using all media was 70.6 hours.

U.S. Internet ad spending in the fourth quarter of 2007 grew nearly 28 percent over the same quarter in 2006 to $7.3 billion, said analyst firm IDC.

For the entire year 2007, online ad revenue grew 27 percent year over year to $25.5 billion.

IDC said that Google’s net U.S. market share dropped for the first time in two years because of a slow down in growth in domestic fourth quarter sales. Google’s net U.S. advertising market share decreased 0.5 percentage points to 23.7 percent last quarter compared to 3Q07.