Gartner on Thursday cut by almost half its worldwide server revenue number for the first quarter and returned IBM to the position of market leader.

In May, Gartner reported that first-quarter server revenue grew by 4.3%, and Hewlett-Packard had toppled IBM from the No. 1 spot. But updated guidance and additional analysis of the data prompted Gartner to lower the increase to 2.5% over the same period a year ago and drop HP to second place.

The latest data showed that IBM accounted for 29.4% of first-quarter global server revenue and HP 28.3%. Total market revenue was $13.3 billion, compared with $13 billion a year ago. The remaining top five vendors and their market share were Dell, 12.3%; Sun Microsystems, 9.9%; and Fujitsu/Fujitsu Siemens, 5.5%.

In terms of server shipments, however, HP remained the leader, accounting for 30.1% of the market, followed by Dell, 22.7%; IBM 13.3%; Sun, 3.7%; and Fujitsu/Fujitsu Siemens, 3.5%. Fujitsu/Fujitsu Siemens was the only vendor in the top five to post a decline in shipments, which fell 2.6% from a year ago. Shipments overall reached 2.3 million units, or 7.6% more than a year ago.

IBM shipments are lower, but its revenue is higher, because it sells fewer commodity systems and more high-end mainframe systems. Nevertheless, the race with rival HP remains close. "We commented in the previous release that HP and IBM continue to vie for market leadership in the worldwide server market based on revenue," Gartner analyst Jeffrey Hewitt said in a statement. "This is still the case, but the updated data shows that IBM maintained the No. 1 vendor position in worldwide server revenue in the first quarter of 2008."