Yeah, CoLinux runs Linux on Windows. Not the other way around. Don't think there is anything that allows you to run Windows from Linux as a taskbar.... would imagine this to be some kind of virtualisation, if it exists.
CoLinux is great, but very buggy.
I have been using windows on my Ubuntu installation from the day i installed Ubuntu. Its pretty striaght forward and you can use ALL microsoft software without any hassle. The only drawback is that you wont get to play any real windows games using the current versions of VirtualBox.
@Arovit.. VirtualBox is the name of the package/software which is available from Sun Microsystems for free(for individual use only.. fully functional). Its available for windows as well as linux. I guess you are talking about 'virtual machines'.
You can download it here http://www.virtualbox.org/wiki/Linux_Downloads
I dont really understand what you mean by "taskbar type". Do you want each windwos app to have its own window under linux. If thats the case, you can use WINE(WINE Is Not an Emulator). There are thousands of windows applications supported by wine (most are games). I am yet to use it, but from reviews, it seems to be pretty good.
for some one who is new to linux i would suggest you download vmware workstation for windows or if you want to install it on linux you have a vmware workstation for linux as well.
install the OS you want to, and learn it without any headache of disturbing your applications. it allows you to take snapshots and revert back to them, and of course your base/host OS is not affected however hard you pound your guest.
once your learn it well go ahead installing it on a baremetal or dual boot