Kubuntu 9.10 i386 Alternate CD is useful for almost all PCs. This includes most machines with Intel/AMD/etc type processors and almost all computers that run Microsoft Windows, as well as newer Apple Macintosh systems based on Intel processors. Choose this if you are at all unsure.
Kubuntu is a free, user-friendly operating system based on KDE's desktop software and on the award winning Ubuntu operating system. With a biannual release cycle and at least 18 months of free security updates for each release, it is the secure, stable computing environment you've been waiting for.