I know the trailer I made was pretty rubbish but the sounds I used on it were from Partners in Rhyme.com you can see their link on the left of my blog. After I'd put the link up they sent me about 150meg of free sounds. They are really good and anyone thinking of making their own trailer, or anything using sounds, like me who writes simple computer games when I'm bored, they are definitely the people to go for for Wav's, loops, or indeed, entire music tracks. Their paid-for music is simply superb. I'd buy some if my youngest and dearest hadn't just trashed her car - again.
Now, with the stuff they sent me, I'm working on my next trailer and this time it won't be so embarrassingly bad. I'm even getting used to the software. This time I won't hurry since apart from You tube there are about six other places to upload it.