Actually, one could always use Image Capture rather than iPhoto to download you camera's images, that's exactly what I still do, always have. As
Raven has found, images/photo's are usually large files and can soon engulf your hard drive. I don't have room to keep all of them on my internal drive. Heck, I don't even see a need to keep them on an external! Download them, view them, cull them, edit a few, get rid of the 'chaff' ans store them on removable disks. What's the point of have five years worth of images in iPhoto? It's not a very good editing app, so you'll likely do any editing, cropping, printing in a real graphics program, anyway. Do you really want to watch a slide show of 1,735 images?
It
can be used to print out some nice 'contact' sheets of a 'roll', store than page with the CD holding the images and dump them from memory. Just depends on what you want to keep at your fingertips, I guess...
So,
Raven, does version four even have an "Empty Trash" menu item? If it doesn't, it might be a lot easier to buy a newer version of iLife. It should still be able to read all those images in the iPhoto Library and you can then easily dump the ones you don't need/want in iPhoto. Of course, if that's the only originals you have, you may have more serious problems!
Perhaps you can retrieve them from the "trash" before the OS deletes them. Just another complication of using iPhoto, IMHO. Apple made it easy to use but hard to adapt as your needs change. But that is usually the case when we demand simple rather than comprehensive.