What Internet Resources Are There
Directly from Microsoft, via FTP there are a number of UNIX to Windows Presentations in Powerpoint and text format. Recently, Microsoft added a number of HTML files at the same location. You can find them mirrored right here.
O'Reilly and Assoc. has an interesting interview with Microsoft's liaison to the UNIX community.
Bristol (makers of Wind/U) maintain an excellent bibliography that contains a number of useful pointers, especially with regards to GUI portability.