Using a virtual partition is slightly better than using a dual boot system. That is because you can keep the specialized operating system (usually Linux) within the main operating system (usually Windows), browse and alternate between the two operating system just using a simple command, and can utilize the advantages of both operating system.
Also you can create project specific discs for enhanced security.
In my (limited ) Mac experience, the comparisons of each operating system are-
1) Mac- Both robust and aesthetically designed OS, the higher price and hardware-lockin for Mac remains a disadvantage. Also many stats and analytical software just wont work on the Mac
2) Windows- It is cheaper than Mac and easier to use than Linux. Also has the most compatibility with applications (usually when not crashing)
3) Linux- The lightest and most customized software in the OS class, free to use, and has many lite versions for newbies. Not compatible with mainstream corporate IT infrastructure as of 2011.
I personally use VMWare Player for creating the virtual disk (as much more convenient than the wubi.exe method) from http://www.vmware.com/support/product-support/player/ (and downloadable from http://downloads.vmware.com/d/info/desktop_downloads/vmware_player/3_0)
That enables me to use Ubuntu on the alternative OS- keeping my Windows 7 for some Windows specific applications . For software like Rattle, the R data mining GUI , it helps to use two operating systems, in view of difficulties in GTK+.
Installing Rattle on Windows 7 is a major pain thanks to backward compatibility issues and version issues of GTK, but it installs on Ubuntu like a breeze- and it is very very convenient to switch between the two operating systems
Download Rattle from http://rattle.togaware.com/ and test it on the dual OS arrangement to see yourself.
DECISION STATS 
Thanks for the commentary – also note that the new versions of R/Rattle/RGtk2 make it much simpler now to install on Windows. The newest RGtk2 takes care of installing the required GTK package and so the user no longer needs to do that step themselves. I would be interested in your feedback on running Rattle on MS/Windows now.
ok. Let me test Rattle again. I think Rattle works ok on a new install but removal of legacy GTK was the issue so let me test it .
Thanks for writing on this
Ajay
Websites-
http://decisionstats.com
Ajay,
You can run Windows on a recent Mac either as a dual-boot system or in a virtual environment. I use Parallels to run Windows so as to use Tableau and occasionally Rapidminer (I never got on with the Mac version) and it works absolutely fine.
Of course what you can only do on a Mac is run OSX. As for price, there is no low-end offering but like for like they certainly aren’t as far off now as when I got my first one 20 years ago.