work with linux in windows

I have windows system , I want to work with unix , i cannot install unix becasue of drive partition , I am wondering if there is any software which runs unix under windows like oracle I can start it and do all my work similarly is there any software which will start linux and I can do all experiments i need , more I am looking for free ware

You can achieve this by doing Virtualization.

http://www.andlinux.org/
http://wubi-installer.org/

Wubi lets you install Ubuntu as a file on your Windows system. Want to remove it? Just delete the Wubi file
Another option is Portable Ubuntu (there are other flavors available) which lets you run Linux inside Windows a little more seamlessly than virtualization.

You could install VirtualBox and install a Linux distribution in a virtual machine.

As a completely different approach (depending on what you really want to do), you might want to consider Cygwin

If all you want to do is be able to run standard unix/linux commands and experiment with them, then this could be a far less resource intensive task. This will allow you to use all the standard commands (find, ls, tar, awk, grep, perl, ...) from the Windows command line. To do this, all the commands are built to be true Windows executables. As such, you do not have the overhead of running 2 complete operating systems simultaneously. You can even run the X-Windows System that can integrate seamlessly with the Windows view, so your X applications appear as native Windows applications.

The one thing Cygwin is not good for is running native Linux applications (especially graphical applications) "out of the box". For example, if one of your friends suggested you try Tux Racer, it will not work under Cygwin (however there is a Microsoft Windows version of it, so you don't really need to try to run it under Cygwin). So far I have not found any commands that are not available under Cywin or that don't have a native Windows version.

srini carry wrote: i cannot install unix becasue of drive partition,

What does that mean? You could add an additional drive, coulnd't you?