You can find out about any exam or track requirements by visiting theMicrosoft's MCP page
The syllabus won't change for the current MCSD track, so up-to-date study material should take you far. Personally, I would recommend that you take the Visual Basic (or C++ exams) before taking Solutions Architecture, as the Solutions Architecture exam is generally considered much more difficult.
I wholeheartedly recommend the Transcender prep test for Solutions Architecture - it will help you out immensely. I'm not sure what to recommend for reading on the C++ side, but if you're looking for good information on the Visual Basic exams, you might want to check out my book MCSD In a Nutshell.
This was first published in March 2001