i wrote the HQCT control software in delphi (5, now on Delphi7), feel free to download the source from www.datalex.be, www.xtronic.be or http://users.telenet.be/putput, the last one is a version derived from mine and reworked. I am finishing a new release that no longer requires an extra dll for the USB.
How much data do you want to store? Mysql sounds OK but you might get away by using files and load them in memory when needed.
Welcome to the gang,