Thought I'd add a little to the battery discussion.
I bought a "1930mAH gold" battery from ebay.

It was working very badly, so I decided to take a look under the gold sticker, here's a picture of what I discovered.

The pic isn't great but you can easily make out "750mAH" on the battery's casing.

Had to laugh really - I only spent £4 on it after all.