Best to go for an MPEG output. Adobe Premiere has a setting for "video for web" which will compress it to a suitable size for the internet.
If you try to put the AVI on the web it will take all week to upload and will probably be bounced by the site. In addition, 1.4GB for 5 mins is a bit too much for anyone!
I would recommend trying a different package as Adobe Premiere is pretty high end (and expensive) to use just for putting photos/stills to music. Have you tried MS Movie Maker built into XP?