Install Win XP Pro in NT server domain

I will be upgrading a large number of users from Win 98/95 clients to Win Xp Pro. All users log on an NT server domain and have a logon script attached to their account to update the antivirus software on their pcs.
In order to keep using the logonscript functionality, will I need to upgrade my server to win 2000 since file system files used by antivirus software no longer function between the 2 file systems?
I know I can create an image with all the applications and administrative tools required for a standard desktop environment by using RIS or sysrep.
Is it possible to install an SMS on the NT server and use it for deploying the XP migration or do I have to run the image on all pcs? Will the SMS be able to work in a similar environment?

Thanks for your time