The highest wattage I'm using in any system I have is 350W. Of course they are quality wattages. I do have to pick a bone with Dan, though. A lot of the PSU's he's reviewed are basically going off the label, and not through actual testing.
Not all PC salesmen are bad. I've had a few here in town that have consistantly recommended stuff that has been outstanding. The last 4 boards I've purchased in town (Abit IS7-E, MSI 865P Neo, Gigabyte GA-7VAXP Ultra, Abit NV7-133R) have been recommended. All were awesome boards. Then again, you've also got folks that really have no clue what the hell they're talking about. Quality is just as important, if not more so than quantity.