I've read this passage on Cisco web site:
To use PEAP authentication, you must install the PEAP supplicant during ACU installation or Service Pack 1 for Windows XP. This Service Pack includes Microsoft's PEAP supplicant, which supports a Windows username and password only and does not interoperate with Cisco's PEAP supplicant. To use Cisco's PEAP supplicant, install ACU version 5.05 or greater after Service Pack 1 for Windows XP. Otherwise, it will be overwritten by Microsoft's PEAP supplicant.
Which are the differences between Microsoft and Cisco supplicant?
Thanks.