Funny you should mention this. I want to do this exact thing (change my awful middle name to Mum's maiden name). My first name is great but my middle name is so bad I can't even mention it to anybody. How did you go about doing it? And what was your original middle name, if you don't mind me asking?
It was something that I had wanted to do for literally years, but just took a long time to get around to it - Infact, I'm pretty sure my Mum hadn't even changed her name back to her original surname when I first decided I wanted to do it - In the end it wasn't as difficult as I assumed it would be...
I was born in Perth so had to send off a form to WA Birth, Deaths and Marriages (that I found online) requesting the change and all that stuff and paid about $200 - They sent back a new cerfiticate and from there it was all about updating licence, ID, bank cards etc etc. It's not that hard to do it once you finally get the ball rolling...
Best part was that I didn't tell Mum about it and when the certificate came in the mail with my new name I just sent her a photo of it
My middle name was Ryan, which wasn't bad in itself - but aurally is sounds awful when coupled with my surname (too many "I" sounds), and I wasn't named after anyone in the family or anything so there was no one to offend....
Plus, Mum's surname is Dare - So now my middle name is actually awesome