How secure is a .htaccess on a folder (and it's sub folders)?

[eluser]littlejim84[/eluser]
I'm making myself a little online task list thingy, but want it to be secure from the public. It will most probably be something like <my domain>/manager/. This manager folder will include other sub folders too, which I also want secure with a username and password.

I was personally thinking .htaccess authorisation would be a good and painless way of doing it... But is it secure? Is it as secure as anything I could do inside CodeIgniter? I'd like a solid secure way of keeping what's past <my domain>/manager/ secret.

Any tips/info/experience?