Mac OS 8.1 retails for $99, while the Microsoft software suite goes for $499. The rebate--essentially 5 percent off--extends through June 30. It does not apply to upgrade purchases.
The rebate appears to be another example of cooperation between the longtime rivals.
Last August, Microsoft said it was making a $150 million investment in Apple, a point of some controversy among Mac lovers. When interim CEO Steve Jobs broke the news to a crowd of Apple loyalists at a company trade show, it brought on sustained boos.
The announcement also drew the interest of the Federal Trade Commission. Regulators apparently are concerned about anticompetitive ramifications.
But more and more, the two companies have been working in tandem at Macintosh industry events. Microsoft also employs as many as 200 engineers to write software for the Mac, a platform that commands one of personal computing's most loyal user bases.
Introduced in January, OS 8.1 includes an improved drive file system called HFS+ that increases the space available for files and support for an industry-standard file system called UDF (Universal Disk Format), which is required for reading files from DVD drives. The upgrade also fixes minor bugs and improves Java compatibility.
It also includes the ability to launch applications more quickly, according to Apple, including Microsoft applications optimized for the Mac.
The Office 98 upgrade comprises a refresh of the full suite of Microsoft business applications: Word, a word processing program; Excel, a spreadsheet; Outlook Express, an email and newsgroup reader; and the PowerPoint slide presentation program.
Release in late March, it seeks to emulate the look and feel of Macintosh. For example, Office 98 tables matches the gray of the Mac color scheme. The previous version of Office for the Mac, ported from Windows, was not "Mac-centric" enough, Microsoft has admitted.