SAP ( SAP) said first-quarter earnings shot up 23% from a year ago on surging software sales in the U.S.

The German business software giant earned $272.5 million, or about 92 cents a share, in the latest quarter compared with earnings of $221.3 million, or 71 cents a share, last year. Overall revenue rose 2% to $1.9 billion. Pro forma earnings were also about 92 cents a share in the latest quarter.

Driving the performance was a 45% jump in first-quarter software sales in the U.S., a gain that came out to 65% in constant currencies. European and Middle Eastern software revenue slipped 4% from a year ago, or 3% in constant currencies. Total software revenue was $321.2 million, up about 5% from a year ago and up 11% in constant currencies.

SAP reiterated full-year guidance, calling for full-year software revenue to increase 10% over 2003 and pro forma earnings of about $4.99 to $5.12 a share.