The only other thing you might check outside of whosrdaddy's good answer is how the CGI program (really a text program with special rules) behaves on the new OS. Especially with the 64-bit OSes, Microsoft has been "removing features" (I have things that worked perfectly on 8.1 32-bit that don't work well at all on the 64-bit version for this reason or that when I transitioned) in a number of ways. Also, they haven't been too consistent with keeping bugs out or fixing them. For instance, faq102-7109 contains a text driver that switches the color to black before CR/LF because of the "ribboning" of color out to the edge of the screen (a bug) that was introduced as of Windows XP SP3.
Anyhow, just try to fire up the program on the new OS and be sure it still takes input and writes output as was expected on your original OS.