It's been awhile since I built a PC, but as I wanted a state-of-the-art system that runs Windows XP, I purchased an ASRock Z68 Pro3-M motherboard along with an Intel Core i7 2600K processor, 8Gb of memory and a couple of 2.5" drives (64Gb 6Gb/s SSD + 750Gb 3 Gb/s). I also obtained a Sentey mATX case that turned out to be a disaster as the power supply radiated so much electrical noise that it interfered with the doorbell and other devices. It was also useless as a desktop as there was insufficient heat extraction and the front LCD panel did not work completely. The Sentey case was returned.
I could not find a mATX desktop case locally, so I swapped the guts around of a few old computers and ended up with a reworked HP DC5000 case that has one external 5.25" bay, one external 3.5" bay plus an internal 3.5" bay. I've used a 3.5" converter to two 2.5" bays for the internal 750G drive and a StarTech trayless hot swap mobile rack for the SSD drive (external 3.5" bay). I replaced the existing power supply with a 1U Athena FlexATX 300W unit and ordered two 60mm x 25mm fans and two 40mm x 25mm fans, both from SilenX, to replace the existing fans I added, or in place, that are rather noisy.
After several attempts, I installed XP on a 17Gb partition and Kubuntu 11.04 on a 30Gb partition of the 750Gb drive; when everything is loaded, I'll transfer these OS's to the 64Gb SSD.
Installing these OS's proved to be something of a challenge as I was unfamiliar with the BIOS settings required. After numerous attempts I discovered that I had to have the BIOS PCI/ROM priority set to EFI. When running the Kubuntu install CD, select UEFI [DVD_drive] to install it in GPT mode. For XP, I set the SATA mode to [AHCI] and when booting with the XP CD, select AHCI [DVD_drive] to install it in MBR mode. If these setting are changed after installation, XP will not boot.
The XP install CD does not contain the necessary drivers for this SATA mode, and I had to temporally plug in a 3.5" floppy drive and create a SATA/SATAII/SATA3 driver diskette. This is done using the ASRock DVD that is packaged with the motherboard. During POST at boot-up, press F11 and select DVD/CD device. Press 'Y' when prompted if you want to generate a Serial ATA driver diskette. When the XP installation CD starts, it loads a range of drivers with the comment to press F6 to add additional drivers. Pressing F6 allows the SATA driver to be loaded after loading its own drivers. There seems to be no option but to use a floppy diskette for this purpose unless you can slipstream an XP install CD.
Loading XP after I had installed Kubuntu meant I had no dual boot or Grub loader. I loaded a Parted Magic CD, selected the Extras Menu and ran the Grub2 bootloader. I then selected "Find OS's" so that I could boot into Kubuntu. Once up and running I re-installed Grub2 and installed a Grub bootmanager/configuration utility, chose XP as the default Boot OS, and rebooted.