I have C7 and C7.5 installed in the same computer, using 7.5 for new projects and 7 for those started in C7, just to avoid surprises with Customer’s jobs.
I can run one or the other, no problem. I wonder if I could install 7.07 anyway, without affecting anything in 7.5
C7 and C7.5 can safely co-exist, as well as earlier versions of Cubase (C6.5, C6, C5.5…etc). The installations and updates do not interfere with each other.