Fill flash - 380EX?

So I'm shooting a wedding for a friend this month. Super low end, i'm not getting anything out of this except experience. I wasn't even asked to be the photographer. I just knew they couldn't afford one and planned on using disposables only (yikes) so I figured it'd be a good time for me to work on shooting people, since I usually shoot bugs

The only flash that I own is a 380EX. No, it's not the most powerful thing in the world, but it's helped me out quite a bit. If i'm no more than 15 feet away, would this be an acceptable fill flash? I don't have any experience with fill flashing, so I'm going to rely on you guys and some practice shots a few weeks before the wedding.

By they way, I'm borrowing a 550EX from a good friend for the wedding, so I'll be practicing with that for the actual wedding, but I'm wondering if my 380 would do the job just fine. Would I need a diffuser? If so, what do you suggest (low budget).

There is nothing wrong with the 380 . Except it eats batteries . In it's day , it was one of the best .
Mine works as a fill , but I had the tube replace about a year ago .
The strenght of the flash depends on age - things deteriate , dust build up in time , plastic cover clouds up .
I would cycle a few times to clear up and have a few sets of batteries .
As far as batteries go - A rechargeable is 1.2 volts and a regular is 1.5 volts . Since the flash was designed for throw - aways stick with them . Faster recharge times

as I noted in the original post, I've never used a flash as a fill light only. I've always just used it in doors to bounce off the ceiling and get acceptable in-door results. Is there a link to proper techniques for doing fill flashes?

At the top of flash forum . read 101 and 102 and play with it .

appreciate it

for whatever reason, I always fail to read stickies...