here's my winnt.sif file:

[Data]
    AutoPartition="0"
    MsDosInitiated="0"
    UnattendedInstall="Yes"

[Unattended]
    DisableDynamicUpdates = Yes
    UnattendMode = DefaultHide
    OemSkipEula = Yes
    OemPreinstall = Yes
    Repartition = No
    FileSystem=*
    UnattendSwitch = yes
    WaitForReboot = No
    DriverSigningPolicy = Ignore
    NonDriverSigningPolicy=Ignore
    Hibernation = No
    OemPnPDriversPath="Drivers\006_storage;Drivers\006_storage\3ware;Drivers\006_storage\3ware\6000;Drivers\006_storage\3ware\7k&8k;Drivers\006_storage\acard;Drivers\006_storage\acard\6280;Drivers\006_storage\acard\6290;Drivers\006_storage\acard\67160;Drivers\006_storage\acard\671x;Drivers\006_storage\acard\6880;Drivers\006_storage\acard\6890;Drivers\006_storage\acard\68x5;Drivers\006_storage\adaptec;Drivers\006_storage\adaptec\aac;Drivers\006_storage\adaptec\aar1210;Drivers\006_storage\adaptec\i2o;Drivers\006_storage\adaptec\u160;Drivers\006_storage\adaptec\u320;Drivers\006_storage\adaptec\u320r;Drivers\006_storage\ali;Drivers\006_storage\amd;Drivers\006_storage\highpoint;Drivers\006_storage\highpoint\hpt366;Drivers\006_storage\highpoint\hpt371;Drivers\006_storage\highpoint\hpt374;Drivers\006_storage\highpoint\hpt3xx;Drivers\006_storage\highpoint\rr182x;Drivers\006_storage\intel;Drivers\006_storage\intel\eide;Drivers\006_storage\intel\sataraid;Drivers\006_storage\intel\u320r;Drivers\006_storage\ite;Drivers\006_storage\lsilogic;Drivers\006_storage\lsilogic\megaide;Drivers\006_storage\lsilogic\mraid35x;Drivers\006_storage\lsilogic\mylex;Drivers\006_storage\lsilogic\symmpi;Drivers\006_storage\nvidia;Drivers\006_storage\nvidia\eide;Drivers\006_storage\nvidia\raid;Drivers\006_storage\promise;Drivers\006_storage\promise\fasttrak;Drivers\006_storage\promise\fasttx2k;Drivers\006_storage\promise\sx4000;Drivers\006_storage\promise\sx6000;Drivers\006_storage\promise\ulsata;Drivers\006_storage\promise\ultra;Drivers\006_storage\qlogic;Drivers\006_storage\qlogic\12160;Drivers\006_storage\siimage;Drivers\006_storage\siimage\3112;Drivers\006_storage\siimage\3112r;Drivers\006_storage\siimage\3114;Drivers\006_storage\siimage\3114r;Drivers\006_storage\siimage\3124;Drivers\006_storage\siimage\3124r;Drivers\006_storage\siimage\649r;Drivers\006_storage\siimage\680;Drivers\006_storage\siimage\680r;Drivers\006_storage\sis;Drivers\006_storage\sis\eide;Drivers\006_storage\sis\raid;Drivers\006_storage\via;Drivers\006_storage\via\eide;Drivers\006_storage\via\ideraid;Drivers\006_storage\via\miniport;Drivers\006_storage\via\sataraid;"

[GuiUnattended]
    AdminPassword=
    EncryptedAdminPassword=No
    OEMSkipRegional=1
    TimeZone=110
    OemSkipWelcome=1
    ProfilesDir="%systemdrive%\Documents and Settings\"

[SetupParams]
    Skipmissingfiles=Yes

[RegionalSettings]
    LanguageGroup=1
    SystemLocale=041d
    UserLocale=041d
    InputLocale=041d:0000041d,0409:00000409

[Identification]
    JoinWorkgroup=MSHOME

[Networking]
    InstallDefaultComponents=Yes

You have to provide answers for AdminPassword, FullName and OrgName... and maybe some more, I'm not sure.

Look there