I've never got this one straight, but I'm sure one of you kind and clever people can enlighten me. I always find myself putting things like:

'Hello, Fred,' she said; then, more quietly, 'hello, George.'

What I don't know is whether that second 'hello' needs a capital letter or not. And what the rule is about it. Does it depend, for example, on whether it's a new sentence or not, in the dialogue? So that even if the first example does need a new capital for 'hello', this one might not need a new capital for 'you bastard':

'Hello, Fred,' she said; then, more quietly, 'you bastard.'

AAAGGHH!! Help!

Rosy

I don't know for sure, but I would have done as you're suggesting, Rosy: upper case H for "Hello George" because it's a new sentence of dialogue, and lower case y for "you bastard" because it isn't.

Deb

<Added>

For instance,

"I think it's quite cold in here," she said, reaching over to pick up the stapler from Susan's desk, "but if you want to open the window it's fine."

Deb

For what it's worth, I'm with Deb.

'Hello, Fred,' she said; then, more quietly, 'hello, George.'

I think your problem here is that semi-colon. How would you punctuate this line if you hadn't interrupted it?

Speech = Hello Fred; hello George.
This would lead to: "Hello, Fred," she said; then, more quietly, "hello George."

Speech = Hello Fred, hello George.
This would lead to: "Hello, Fred," she said, then, more quietly, "hello George."

Speech = Hello Fred. Hello George.
This would lead to: "Hello, Fred," she said. Then, more quietly, "Hello George."

I hope this makes sense!

For what it's worth, I'd go with the third one.