One of my best friends is super talkative and annoying...help please?

I'm going to try and keep this as short as I possibly can because I could literally go on all day with this girl's problems. First off, she's a talker. I've accepted this. But it is RIDICULOUS how much she talks and how stupid some of the stuff she talks about is. A lot of guys (and people in general) are turned off by this because she's such a ball of energy, but she doesn't understand that she's a LOT to take in, and she doesn't get that she has a problem with being a nuisance (but she recognizes that other people don't like her).

There's hundreds of examples I could use but I'll just go with last night: she invited me over last to job search on the Internet with her, but she wouldn't STFU the entire time so I couldn't get anything done. Then we tried to watch a movie...I don't understand half of what went on because she wouldn't stop talking. Then she started taking out the pull-out. I asked if she was planning on sleeping there since I never said I was going to sleep over. She told me it was for me and when I told her that I was going to go home to drop my backpack off (actually it was to have some freakin' alone time away from her), she insisted on coming with so she could smoke a cig along the way.

Normally I would just tell someone like this to shut up, but she's a VERY fragile, delicate, sensitive person. If you say the smallest thing, she takes it so negatively and is very hurt and clams up. I don't want to hurt her feelings, but I need to let her know she is annoying the **** out of me and others. How do I do this? Thanks!