to help reduce the size of your png screenshots, if you're not going to switch to jpeg, you can use png crush, which I think is on sourceforge, but google can find you a link. It's a command-line program that further reduces the size of png-24/32 files. I've found that it doesn't really compress png-8 files created in fireworks or imageready/photoshop much. I think it's also available for linux.