Tiger Server and Tiger "client" run the same on any given pice of hardware.
The Server-OS itself will run fine, the question is what will you be doing with the server?
Network services like DNS, DHCP, NAT, Firewall etc. will run easily.
FileSharing services like AFP, SMB, NFS, FTP will run fine too, if not too many users (50) are connected.
WebServer >> fine.
Mail server >> as long as you're < 50 users, also okay.
No use in hosting Xgrid services though.