Another thing to bear in mind is that if the slides are Kodachrome then they will be especially difficult to get good results from.
I'd second this; I've recently bought an Epson V500 to replace my Canon LiDE 80. For negatives I've got to say I'm really chuffed-the quality is excellent, and I haven't even come close to learning how to get the best out of it. However I tried scanning some of my mother-in-law's Kodachromes from the 1950's-'80's and had the well-documented problem of them being too dark (Google Kodachrome Slide Scanning and all will become clear). Shots from sunny skiing holidays were just about workable; anything else was just impossible to get a useful scan from (even if I ramped the brightness & contrast to the maximum settings). These were all well-exposed shots that have been stored properly-no fading or scratches to worry about, but still impossible. I've read that Vuescan is meant to do a better job, but I couldn't get on with it, and with the extra time involved, it really would take an age to get decent scans.
The advantage to me is that I'm not going to be asked to scan 3000+ slides
I have read of several people who have found that a good way to digitise Kodachromes has been to use a slide projector and to then use their digicam to photograph the projected image. Perhaps that would be worth a try if they are Kodachromes.