Your vista partition is a completely seperate operating system from your windows 7 partition
 
the software on each partition is completely independant, meaning you can have the same application on each OS partition or different applications that do the same thing.
 
Its almost the same as having two computers, 1 running Vista and 1 running Win 7, they're completely independant and have nothing to do with each other.
 
So yes you can keep running onecare on vista and do what ever you like on your win  7 partition as they have nothing to do with each other.