The best one that I've run across (and the one I use) is ABBYY FineReader Pro, but it's pricey at $300 after a 2-week trial. Its primary competitor, ReadIRIS Pro is considerably less at $130 after a 30-day trial. The final one I'll suggest is Simple OCR, which is free. (NOTE: Ignore the $1,200 price tag listed on download.com...that's the handwriting recognition portion which comes as a free trial...the OCR software itself is free.) It's not as powerful as the others, but usually receives a good accuracy rating and you really can't beat the price.
Hope this helps,
Can anyone recommend any software for converting scanned documents or pdf files into a MS word document? In the alternative, could any recommend similar software for converting scanned documents in Corel wordperfect files?