only Windows XP Pro is capable of joining a domain?

I work in the IT department of a call center/answering service and our operator stations are running windows 98 SE. We would love to buy new computers, but it would be very difficult, if possible at all (not to mention kind of stupid) to put windows 98 on them. Our main server (DHCP, file server, etc) is gentoo linux. The operators put in their username and password then the samba domain on the gentoo server validates their password, then maps network drives (if they have the right permissions) and also gives them other permissions based on the login. and also runs some batch files if needed for that use. Is it true that only Windows XP Pro is capable of joining a domain like I just described? And if so, would there be any major changes that would need to be done with the configuration on the server side to make this work? We are planning to move to VoIP, and make some other fairly significant changes to our systems in the near future. I just want to educate myself so I can start experimenting. Any suggestions or links would be greatly appreciated.

IIRC, Windows 98 was able to work with Windows Domains, but the whole domain thing has moved on by quite a long way since then. I remember reading that there were issues with mixing Windows 98/2000 machines on a samba domain with Windows XP, of course these were a long time ago and may well have been addressed now. You would still be safest setting this up for XP Pro only.

XP Home is right out.

Is there no chance of moving everyone onto a Linux/*nix based system? If you did that you wouldn't even have to use Samba to do central account management.

I wouldn't mind (neither world any of my IT co-workers) not having any Windows computer there at all. But the software used by the operators doesn't offer a *nix version. And it's highly proprietary so it's not like we can look into the code very easily. But Windows XP Pro will log into a domain like I mentioned before? That would atleast let us get rid of tons of outdated hardware.

Yes, windwos XP will log onto your domain. That's how I have my windows machines configured, and their domain is managed by Samba on CentOS.