Why would you want to change the php.ini file? You're opening yourself up to issues. Think of it this way: 2MB is a lot of information on a slow connection. When uploading a file, you can't do anything else (in that tab of the browser).
Now, what happens when an internet connection is reset or times-out during the sending? If they're sending a 16 MB file, and only 15MB of it is uploaded, and they retry 3 times, they've now put 45 MB on your server that won't be removed for a bit and possibly taking up space for other uploads.
by raising the php.ini script, you're going to end up with more lost / dropped connections.
Your best bet is to allow anonymous FTP access to a folder on your server (and nowhere else) and include either an online FTP program (Java) or give them the anonymous access info and let them upload it themselves. Then, they submit a form with the name (not the full file) of the uploaded file. Your php script then looks in that anonymous folder for that file, and can do what it needs.
That's a much safer solution since you're now using a better protocol for sending files; however, almost any file can be transferred. The trick is to use a cron-job to remove all "unwanted" files or file-types every 5 minutes (or hour) and to do some data verification in your php script.
So please, don't change your php.ini. It can cause more problems than you think. Think outside the box on how to achieve your goal of allowing a 16MB or 1GB file upload.
