now my pc in windows7 and i want to install windows vista but installing time to showing
this computer does not have enough space for temporary files windows installation need at least 464 mb space on any partition for temporary files.
Why would you want to install Vista when you have W7?
In any case you will need to format your W7 partition before installing Vista which will give you the required space.
Don't forget to backup all your data files to an external source before you start.