rolling back to earlier ver of C++?

[bDAWg]

hi
have read that allowing VCRedist to overwrite newer version of C++ sometimes fixes a IL-2 COD install that will not launch ...was wondering if there's a danger of screwing up other programs by doing so?
and I was also unable to find in my conf.in file any reference to what version of DX the game is set up for ...I'm using XP so it should be DX9.. correct?...is it supposed to be in my conf.in?
thanx