At this time I only collect vintage PC software, especially if it's made by Microsoft. Therefore, I am generally interested in obtaining anything that is not available elsewhere yet.
Tandy/Radio Shack part 90-0476
This is Microsoft Windows, as stated in Radio Shack catalogs RSC-18 and RSC-19.
IBM parts 9811 and 9793
Both are mentioned in IBM's PS/2 and PC product reference version 4.0 from April 1987. 9811 is "Microsoft Windows (5.25in)", 9793 is "Microsoft Windows for Personal System/2 (3.5in)".
Any other piece of Microsoft/IBM software not yet available publicly
Especially interested in pre-release builds of Windows before Vista, IBM OS/2, MS/PC-DOS, applications and games for these operating systems, etc. Contact me if you have anything that fits into this category.
Issues of vintage computing magazines between 1982 and 1990
Especially interested in magazines about the PC and compatibles. If you know of scans being available online or you want to provide them yourself, please contact me.