Time Warner the owner of AOL, today announced it plans to Separate AOL’s ad operations from its dial-up access business.

Time Warner which reported earnings today,  reported that the 4th quarter of 2007, was AOL slowest quarter of advertising growth.

AOL’s $620 million in fourth-quarter ad revenue represents a year to year increase of less than 10 percent.

AOL’s ad revenue grew nearly 50 percent a year earlier.

AOL had 9.3 million paying subscribers as of Dec. 31, a third of its peak of nearly 27 million in 2002.

If AOL sold off its dial-up business in the U.S., as it already has done in Europe, AOL maybe more attractive to potential bidders, including Google Inc., which already owns 5 percent of AOL and has a right to trigger an initial public offering of that stake in July 2008.

Full-year growth for AOL ad business was 18 percent in 2007, compared with 41 percent the year before.

Google’s ad revenue grew by 50 percent in the quarter ending Dec. 31 and 56 percent in the full year

Microsoft’s ad revenue increased 38 percent and 32 percent, respectively.

Yahoo’s ad revenue increased only  6.7 percent in the 4th quarter against 2006 4th quater, and 8.2 percent in the full year.

Yahoo remains, however, second only to Google in terms of total ad revenue.