I don't have first-hand experience with the Antec 420W power supply, however, I have reviewed GlobalWin's YCC-8870 which comes with the Channel Well CWT-420 (Channel-Well Technology 420W Power Supply) unit installed. As far as today's standards go, this power supply really pushes the envelope, complete with the aforementioned 245W of power on the 3.3v and 5v rails. This is more than 50W higher than what AMD
recommends for even Athlon XP 2000+ systems. Bottom line: this power supply is incredible in and of itself, and to top it all off, it comes with the quality construction and name of Channel Well/Sinotech AND it pushes more power out than just about every other 'name brand' power supply available. For $49, $39, $44, or whatever price (under $50) it is, it's a steal. Check out
VN Roundup's Power Supply Selection article, and notice this power supply (near the very top)
Edit: As far as the Antec/Sparkle OEM note is concerned, sure, you've quoted that one review, however, honestly, I think the information
may be incorrect. Usually when you have several companies piggy-backing on power supplies from another manufacturer, they don't tend to change the naming scheme much/at all. As such, it is obvious that AOpen, and Sparkle, among other smaller companies use power supplies manufactured by Fortron/Source (FSP Group), hence the 'FSP' designation for all models. On the same note, it is obvious that American Media Systems, and Sinotech, among other smaller companies use power supplies originally MANUFACTURED by Channel Well. I am pretty confident that Channel Well is the original manufacturer, not just a rebadger of Antec power supply equipment. But again, I reiterate, if my stance is true, that this power supply (CWT-420) is still a very high quality one indeed. You should not worry about its quality/performance, however, the seller's authenticity is a whole different question.
Peace