Battery not charging on Acer Aspire One

Well, I finally took this one off line power to do some tests in preparation for traveling with this. I wanted to check out my wireless broadband. Put on standby, and it was dead a few hours later. Now I have it plugged in, and I can see on the power monitor that it says it is charging (and can detect the presence of the Acer battery and also detect when it is out).

It is pegged on 0% (more than half an hour now), and the computer shuts off immediately, consistent with a 0% battery.

Any way to tell whether the battery or the charging system is at fault, lacking another battery?

Also, does anyone have experience with BuyNow.com for returns outside of 14 days (been more like 21 now- yeah, I know I should have checked earlier). They have it at my local MicroCenter for the same price, so I'm going to get one there.

Cheers.