Hi DJ,
I briefly used Corel Linux about a year ago, which had this facility. I wouldn't have thought OpenLinux would be that different.
The running within Windows thing was a bit of a red herring. What actually happens is that the Linux file system is able to use spare space on a normal FAT32 partition. When you want to run Linux, you click an icon in Windows which closes down and restarts in Linux.
Once you are in Linux, you get a full blown Linux system which can be configured as a workstation, a file server, a mail server or whatever else you need.
I hope this helps.