Okay, here's the bad news. Most business cards are small and printed well, for the small size of the card - but poorly for digitizing, especially if a cmyk process print. I do not use coreldraw - but scanning and converting to vector format is familiar technology and not all that different in Illustrator, Flash or Coreldraw.
The converting technology autotraces an auto smoothed line based on the pixel information. The more pixels the program has to work with, often the better, more faithful, the result.
The issue is that imperfections you may not see with the naked eye - the scan DOES see. If you want the vector art on point, converting scans of business cards can sometimes be unworkable.
I've gotten to where it's usually faster for me to scan the business card and simply re-create it in Illustrator. Tracing the art elements with vector tools. (I'm a talented artist and designer tho, not everyone can hope to do as I do)