I don't really see the reason for using both libraries at the same time in this case.
You can either use Prototype's (well, Scriptaculous' actually) Ajax.Autocompleter and ditch jQuery, or you can use jQuery's Accordion and get rid of Prototype.
Using both libraries at once is not really a good idea, because:
- They can cause conflicts.
- By including them both you force your users to download them both. Which is not bandwith friendly approach.