I took home an old HP Compaq Nx2200 from work and I'm having a hell of a time trying to get Snow running on it (though I read a few posts where people had some success with this minitower). The problems are mostly because of the ATI SB400 chipset (and probably the Pentium 4 531 cpu. The CPU should work with a modded kernel (chocolate_kernel sort-of works) & 32bit mode, but it seems to crash randomly. After upgrading the video to an NVidia 8500GT (I don't think the onboard ATI X200 would ever work) I actually had it booting to the desktop with CI/QE and sound (VoodooHDA) but was running off a USB HDD (seems like USB 1.0 speed) but it would not recognize the internal ATA HDD. I reinstalled iPortable Snow on the USB HDD and some AppleATIATA kext I found and the internal ATA bus was recognized (but as SATA) so I went to clone the USB hdd to the internal HDD but when I go to boot from internal it gives the "Still waiting for root device". It's totally maddening trying to get Snow Leo up on a motherboard that's this old and a chipset not even close to anything Apple has used. I don't really need yet another Hackintosh (I just like the challenge of it) but I'm almost ready to give up on this one!!! I might try Leo or even Tiger both of which ran well on older / non intel chipset ASRock board I had (775DualVSTA / Via chipset I think it was).
Here are things I recommend for getting your older / out-of-spec hardware running:
1. Download and try to boot "iPortable Snow" (there is a Leopard version too) onto a USB drive (must be 8GB or larger). These distros have minimum kexts loaded and problematic kexts removed (like video excelleration and sound). If it runs well with these most basic installs then it might be worth the trouble.
2. Try an older version of OS X like 10.5.x or 10.4.x there were a bunch of custom installer distros with added support for all kinds of weird hardware. I recommend the "xXx" ones because they were like archival releases that included TONs of drivers.
3. Loose that old ATI RADEON, It will never work with Quartz Extreme / Core Image because Apple's Radeon drivers are PowerPC only! It will only work as a non-eccellerated VESA video.
4. Time is money. Don't waste your life trying to get it working (unless you find it phun/enjoyable). I've wasted 100s of hours trying to get OSX running on non-standard chipsets (by that I mean non-Intel because Apple has only ever used Intel chips on it's motherboards). In the end best hackintosh experience you can get will be from a motherboard that has an intel chipset that Apple has used. I've found that most Intel 945 or 965 based motherboards are fairly easy to get up and running on and are very affordable on eBay at this point. Sell your old mobo and put the money towards getting one of these old mobos instead.