VPN – IPSEC/L2TP between Tiger Server and Win XP client with NAT-T involved

hi ! i have panther Server and i want to create a IPSEC/L2TP VPN between my Server and Win XP client but NAT-T is involved (distant users use wifi connection => routers) i had to understand it would not work because of non use of common standards between apple and microsoft for vpn negociation when NAT-T is involved i can imagine to buy tiger update for my server BUT has anyone managed to connect Win XP client to Tiger Server through IPSEC / L2TP when NAT-T is involved ? please tell me YES et how you did it ...