Red Hat Enterprise Linux ES for Small and Midrange businesses

Databases - Leading open source databases: PostgreSQL, MySQL
Development - Environments for C, C++, Java, Fortran with Perl, Python, CVS and Emacs
Engineering - Computational tools including blas, pvm, and lam
File servers - FTP, NFS, and Samba (CIFS)
Mail server - IMAP/POP servers with Cyrus, Sendmail, spamassassin
Networking - Complete suite of network servers and firewall
Printing - CUPS/lpr printing systems
Security - Extensive features including SSL, IpSec, MAC/DAC
Web server - Apache server with numerous mod/php plugins