I do and only too well.
If both were installed on the same machine, shadow copies and restore points would disappear daily. It is what forced me to go to Vista full time and dump XP.
This time, the decision is not so clear cut because moving entirely to Windows 8 will not get me anything I don’t already have, including general performance, and I will be losing stuff that I find invaluable.
I have now disconnected the Windows 8 hard drive and it will stay that way unless I can find a way to make 7 and 8 live together. I am sincerely regretting the decision to let Windows 8 out of it’s VirtualBox and let it run free. It has taken two days for Windows 7 to stabilise itself.
Personal advice? I would not mix the two on one machine, either in dual boot or parallel installation.