Well, according to the article, one needs to concentrate on the individual voltage ratings, particularly +3.3, +5, and +12 volts. Most power supplies (300w) are able to handle typical +12 requirements but I have learned that the 3.3 Volt requirement is lacking in my AMD approved, 300w power supply. This is no fault of AMD's recommendation but simply the severe power requirements of my Geforce256. According to www.geforcefaq.com for the combination of Geforce plus Athlon a 20 amp rated 3.3 volt supply is recommended. (You may be in the same situation with your Voodoo5. I don't know). My supply is rated for only 14 amps on the 3.3 V leg which I think is typical for a 300w supply.
At the advice of another reader at these forums (can't remember his name) I am looking at the Enermax EG-351 (which may have been replace by the PEG-351VE). This supply provides a peak of 30 amps on 3.3 volt line. This is more than enough reserve for me. I think it's about $55 plus shipping.
I have found it very difficult to find discrete specs on PSU's so this is the one that I will probably buy. If you have access to the PSU's that you are considering just read the information on the top and you will know. You can probably purchase by reputation as well. Enermax, Fotron, Sparkle, and Antec all have good reps. A 350+ watt supply from these brands tend to have at least a 28 amp rating on the 3.3 volt line.
On the other hand, if you feel more comfortable, 400 watts won't hurt but you still need to check the individual specs.
You might want to ask for other opinions here at tomshardware and, again, don't blindly trust the overall rating.