Koraks's suggestion to try Epson scan is a good one. I haven't used Epson scan for film scanning with my Epson flatbed; but I often use it for scanning prints and Polaroid photos, and it is reliable, stable, and gives good quality scans. I have actually never tried the film scanning capabilities of my scanner since I have a Nikon scanner for film, but if Epson scan is as good for film scanning as it is for prints, I would use it. Try it and see if it works for you.
If you don't like Epson Scan, I'd suggest Vuescan. It isn't open source, you'll have to pay for it; but it is not expensive and it is the best film scanning software I've tried. It is what I use with my Nikon scanner.