I second the recommendation for VueScan. After a few years, the manufacturer of your scanner will probably abandon you software-wise. I have an old Canon scanner that's at least 5 years old, the Canon software doesn't work, but VueScan recognized it right away. The standard version is $50, but I payed the extra $30 for the professional version which has, among other things, free unlimited upgrades. It payed for itself by enabling me to continue to use my old scanner.
That being said, I guess I've had good luck with the Canon scanner, but I found that there was much better Mac support with my Epson printer.