Microsoft's PC emulation application Virtual PC 6.1 is incompatible with Apple's now-shipping Power Mac G5s, according to reports.

The company told MacFixIt: "Microsoft is working on adding G5 functionality into the next version of Virtual PC, which is currently being developed by the Mac Business Unit."

In a statement attributed to Microsoft by MacNN, the company reveals: "Virtual PC relies on a feature of the G3/G4 processors called 'pseudo little-endian mode' for increased performance when emulating a Pentium processor." G5 processors do not support this, meaning much of Microsoft's recently-acquired software will have to be rewritten to function on Apple's new Power Macs, MacNN said.

Microsoft acquired Virtual PC from Connectix in February this year. Terms of the deal have not been disclosed. While Connectix handled product support for Microsoft for several months, this function passed to Virtual PC's new owners as of August 15. Connectix currently offers no products.

Microsoft recently released Virtual PC 6.1, an upgrade designed to offer Mac users "around 80 per cent" of the performance of Microsoft's Windows-only products on Mac OS, the company said at that time – though not on G5 processors.

The product is available in a variety of configurations. Virtual PC 6.1 upgrade costs £99, while Virtual PC 6.1 without a Windows OS costs £139. Versions with Windows OS's in the box are available as follows: Windows 2000 Professional, £229; Windows XP Pro, £229; Windows XP Home, £199. All the new versions will be available in early September. Prices include VAT.

Microsoft has been contacted for comment on these reports.