Ok, so can I buy these parts I need at Radio Shack. Software Voltage would be so much nicer to have.
I think so.
It is only general Variable Resistor. It is better to buy Potensiometer. Variable Resistor need screwdriver to adjust it. Potensiometer can be adjusted by your finger easily. Asked them B type potensiometer (linear type potensiometer), as it is more suit for this purpose. One B10K for GPU, and one B50K for Memory. Once you have settle the voltage you want, you can replace potensiometer with fixed resistor.
You need to prepare a tools for it. You need AVO (ampere, voltage, ohm) meter (better if you buy digital AVO meter). You need also solder (25-30watt serve well). Cable, at least 1 meter.
IMHO, with respect to the author, the article is not suitable for people who don't have any electronics background. For example: GPU voltage modification, it doesn't explain what is "Starting with the resistance set at maximum, decrease the resistance slowly for Vgpu to rise.". You only need to use 2 pins of potensiometer. Use cable for them. One in the middle pin, and one at left pin (from your view where you can adjust potensiometer easily). Or, better if you measure that 2 pins (before soldering the cable to the board, do not measure it when is already soldering to the board, as the result may not correct, and possible damage the card!!!), it should be ~10Kohm. You need also to solder cable to the Vgpu measure point for easier to read Vgpu. After that, slowly turn the potensiometer (around 5-10degree), stop, run ATITool, increase GPU clock, check for artifact and GPU temperature. Wait for 20-30 minutes. If stable, you can turn potensiometer again, stop, do the same. Watch the GPU temperature closely, you don't want to burn your GPU right. If you satisfy with the result, check the Vgpu, you need it for your reference. Remove the card, remove the potensiometer and its cables from board, measure potensiometer value, buy Resistor with value nearest to potensiometer value, solder the Resistor to replace the potensiometer. Now every thing on board looks nice and tidy again.
That's only for GPU voltage modification only. Repeat according to the article for Memory voltage modification, and you have both GPU and Memory voltage modification.
Remember to turn off PC completely before remove or putting VGA card. It is better to take out the electricity cable from PC, as if you only shutdown windows, it will not cut/off the power running on the Motherboard.
Forgive me to give a long reading above, especially without knowing your electronics background. I am only sad if modification will ruin someone live.
I am not the author of voltage modification article, I am not related to the author. I am just trying to help with my knowledge. Do modification on your own risk. If you think you can't do it, don't do it.
I am still waiting for sure answer whether x1600 series is capable for software voltage modification, before I jump on hardware voltage modification.
Regards,
Arto.
Than this 100mhz overclock (500MHZ -> 600MHZ) would be more if there was more voltage
. 
. Probably I only do voltage modification on GPU voltage, since my Memory is already quite high overclocking, and the board design does not good for put heatsync on Memory chips (4 chips on front, 4 chips on rear. Zalman GPU cooler only can help release heat on 4 chips on front, but not on 4 chips on rear, not balance).
).