Microsoft VPN client enables Microsoft Windows to connect to any VPN server that supports Layer 2 Tunnel Protocol (L2TP) connections with Internet Protocol Security (IPSec).
Download L2TP/IPSec VPN Client (direct)
More Info Guide to Microsoft L2TP/IPSec VPN Client
More Info MS KB325032
More Info MS KB325033
More Info MS KB325034
More Info MS KB325035
More Info MS KB325158
Related Setting up a Virtual Private Network in Win2k/WinXP
Anybody using Win98 or NT or ME yet ? :)