I use the Nikon 5000 ED with the stack loader. I am very happy with it, especially after trying other scanners. Like Bob Thrun says, if you have a lot of slides to scan and you value your time, then get a quality scanner with an auto-loader. The Nikon 5000 ED with the autoloader will set you back about $1,500.
I pick up cans of compressed air from discount stores like Gabriels for about $1 each. I buy a million cans when I can find them that cheap.
Taking great care, I blow each slide clear of dust before it is loaded into the stacker. My 35-year old slides are so old and dusty that I don't worry too much because I know they're going to need some work in Photoshop anyway.
The Nikon stacker jams, yes, but rarely if your slide mounts are in good condition. The problem is that you've got to push only one slide into the scanner from a stack of slides. There's an adjustable slot that permits only only slide to pass through at a time. If you adjust the slot too narrow, the slide can't pass through and it jams. If you adjust the slot too wide, more than one slide can get pushed through at once and it jams. Group together slide mounts of similar size and condition (i.e., thickness) and your stacker will run flawlessly.
My only real complaint with the Nikon 5000 ED slide scanner is that the slides don't feed squarely, they're always at a slight angle. I am consistently rotating the images 0.4 degrees counter-clockwise in Photoshop to level them.
I also have the negative scanner for the Nikon 5000 ED that works well, too.
If you want to see results, check out these photos from 30+ year old slides. All of these photos were originally scanned at 4,000 dpi at 8-bit depth, corrected and retouched in Photoshop, and then converted to 800 x 72 dpi for internet viewing. You can click on the images or captions to see the photo, then click on the photo again to see the original image at full size (800 pixels wide x 72 dpi).
http://www.summitpost.org/trip-report/434125/the-tragedy-of-the-1979-korean-mckinley-expedition.htmlA more extensive collection of my photos can be found here. They're all slides scanned in the Nikon 5000 ED and processed in Photoshop.
http://www.summitpost.org/object_list.php?object_type=3&contributor_id=35019Oh, yeah, if you're going to embark on scanning slides, you better get yourself one of those 500GB hard drives too. I want to say that my original scans off the Nikon are 150MB each. Handling so many gigabytes of data is also problematic if you don't have a clear plan about how you're going to manage the data in terms of handling and storing original scans, TIFF images, JPEG images, internet images, etc.