One way of using dual-system is use Virtual machine. One such practice found useful is using PUR (portable Ubuntu Remix). Under Vista-32bit and XP, starting is very fast, using is OK.
One real application is to scp or sftp stuff from another Unix/Linux system. Another application is writing script to process document under windows.
One issue bothering still is the access of Windows hard drive only limit to C drive. All other partitions were not found, um ...