Microsoft is offering customers buying a copy of Office 2004 through Apple's UK online store the chance to receive a free upgrade to Office 2008, which ships next year.

Microsoft's Technology Guarantee Programme means that anyone buying a copy of Office 2004 from the Apple Store between 25 September 2007 and 31 March 2008 will be eligible to receive Office 2008 for the cost of shipping, handling and applicable tax, set at £15.95 in the UK.

This offer is only for end customers who purchased eligible software at retail it is not valid for OEM or volume license customers, Microsoft warns.

Customers hoping to exploit this offer should download the terms and conditions here.

Customers must also ensure they retain a copy of the dated sales receipt clearly showing the date and store name where you acquired the software, the original product box top with the product name and barcode clearly identified must also be supplied with the application, or it will be refused.

Finally, customers must mail the completed form, payment, and all required proofs of purchase in the same envelope by 15 April, 2008.