A version of OS/2 2.0 from Microsoft, not IBM, just surfaced on eBay. This pre-release version came out after Windows 3.0. How much might you be willing to pay to own a piece of operating system history? Would you pay two-thirds of a grand? No, us neither, but fortunately for posterity, Reg reader Brian Ledbetter is. He wrote to tell us that he bought the ULTRA RARE: IBM / Microsoft OS/2 SDK Version 2 Pre-Release 2 for v1 Users [Beta] for a non-trivial six hundred and fifty of your U.S. dollars....