I`ve used SuSE 8.1 on a PIII system and found it OK. Like most Linux flavours it can be dificult in some ways but generally its installer and package updater work well. The Red Hat distro is a little less polished but still not bad or you could look at Slackwares offering. To some extent your choices are influenced by how you intend to get the O/S. The Linux distros are available as free (large!!) downloads or frequently given away on coverdisks and with text books. When you say secure do you mean system stability or security from hackers/viruses? Linux if set up well is generally more stable than windows but still has tantrums now and then. Viruses are not currently reguarded as a big problem due to the nature of the system but a Linux box can still be vulnerable to a hacker if it has not been well set up.