WPA authentication works only with MacOS clients

Hello all, I'm using WPA with EAP-TTLS and PEAP with a MacOS .Authentication works fine (even if enough slowly). The problem is that I can't authenticate WinXP client. I've readed that for using EAP-TTLS are required some other supplicant like SecureW2. Is SecureW2 required also for PEAP? Thanks for attention Best Regards, Josh