I had a devil of a time getting Linux working on a Dell Optiplex GX620, which has the Intel 945G chipset. Serial ATA and builtin video and sound were the main problems. Fortunately, the 2.6.15 kernel and the latest Fedora packages support everything we need. Unfortunately, it takes a particular configuration. You will have to build your own kernel for this one. Maybe soon Fedora will have those options on by default.
Quickstart
If you don't want to build your own, I've made available the kernel build I'm using. It was built using Fedora Core 3 with gcc 3.4.4. I can't guarantee anything if you use a different distro (or, really, even if you use FC3).
title Fedora Core (2.6.15.1umesh)
root (hd0,1)
kernel /boot/vmlinuz-2.6.15.1umesh NOHT ro root=LABEL=/
initrd /boot/initrd-2.6.15.1umesh.img
Kernel configuration I pieced together the following kernel configuration for the 2.6.15 kernel: linux-2.6.15-smp-gx620.config. It excludes a lot of drivers, so if you have another 945G machine or a SCSI card you probably want to edit the configuration first. It's an SMP build because it has the dual-core Pentium D. Sound support is enabled by setting SND_HDA_INTEL=m (the "Intel HD Audio" driver); both SATA-as-SCSI-driver and the regular PCI IDE driver are enabled. The latter is for the PATA DVD drive in the GX620.
Video support
The video driver requires an updated version of the i810 video
driver. This can apparently be found in the latest development release
of the xorg X11 server (