I won't be able to start for probably a couple of weeks esp. since I know next to nothing about getting the OS on these, but thinking of going with:
GIGABYTE GA-G31M-ES2L
Not sure if I want to do a duo or quad yet. The PSU I'm looking at has way to many connections, though, but I wanted one with a light to get the look I'm going for. Any suggestions on something similar to this without so many wires?
Rosewill RP550V2-D-SL 550W
I just built one for my sister using the
Gigabyte GA-EG31M-S2 it is identical spec wise to the one you listed except for the placement of the FDD connector which you will probably never use it also officially supports a FSB overclock to 1600mhz where the one you listed is does not mention 1600.
Note how close the RAM is the the PCI-e x16 slot. Though I did not mount the board in a G4 case I positioned it approximately where it would be in my DA G4 (which I will make a Hackintosh for myself with eventually) and it looked like the RAM will clear the DVD/CD drive bay without cutting. Especially with a modern DVD drive as they are shorter than the metal bay.
There are some problems which took a long time to figure out. First off you can not do a Vanilla install using EFI v(anything) or the Chameleon bootloader. Though the install will take Audio will never work this way nor will any bootloader work unless you always use the Chameleon boot CD I could never get an EFI to take after hours of painstaking research.
Now that you know what not to do, you must use a hacked kernel. I used Kalyway 10.5.4 and selected the right drivers for the install. Once booted everything worked great; audio (in/out), video, ethernet. I then used OSx86 Tools to update all drivers and to get my CPU listed.
After the install I updated all software with one hitch. It will not take the 10.5.5 update you will have to use another hacked kernel for this. iDeneb 10.5.5 v3 should work instead of Kalyway.
I also installed a Radeon 3870 GPU and it works great! I will definitely use this board for myself in a G4 case but use either a Radeon 3870x2 or GeForce 9800GTX as I want a 24" LCD for gaming.
This is not the first I have built but definitely the easiest. Previously I did a SSE2 only Pentium 4 for my sister. The worst was making the AMD in my sig run 10.4 as many parts have poor compatibility; nForce 3 northbridge, socket 754 Athlon 64 SSE2 only, AGP, Radeon X800XT.
Not sure if I want to do a duo or quad yet. The PSU I'm looking at has way to many connections, though, but I wanted one with a light to get the look I'm going for. Any suggestions on something similar to this without so many wires?
Rosewill RP550V2-D-SL 550W
Rosewill is a solid company never had a problem with any of their PSU's. I have built over 20 PC's for myself friends and family and almost all have used Rosewill. For your build I would get an
Antec earthwatts EA500 it does not have the glowing lights. But it uses a rear mount fan only and is 80plus certified. Which means less energy use and should also mean less heat in your case.
As for the CPU get the Pentium E5200 Wolfdale 2.5Ghz FSB800 and DDR2 1066 memory then overclock the living daylights out of that puppy.

3.33Ghz @ 1066FSB