FreeBASIC
A free 32-bit MS-QuickBASIC's syntax-compatible compiler for Windows, that adds new features such as pointers, unsigned data types, inline-assembly. [Open source, LGPL]
http://www.freebasic.net/
QB2C
QuickBasic to C converter. Installation and programming support, sample and working program downloads, latest releases and sales information.
http://www.bastoc.com/