I actually prefer cross use between Linux and Windows.
Single or dual boot. Either is fine. Personally I don't trust Wine/CrossOver that much in using WIn software (even I heavily hacked them up, just for running .NET-like)
For the Weeaboo's argument; here are mine:
Security - I don't fuck around when come to security. I was one of some first people developed speed attack on Windows 7 via its native printer program to inject malware. Like business office, you said, Weeaboo? What stops this from happening on Linux (or OS-X/BSD and shit tons other UNIX-like). Simple: . You have user, group and others. 777 anyone? Anything that goes beyond main users' need the users password in order to open, write or execute, depend on permission setting. Only Windows Server distros offer a working Privilege system.
Speed - Speed is crucial. Business, again? Right now I'm running 5 non genetic processes on Backtrack, including LibreOffice & 5 tabs Firefox. CPU & RAM?
Almost everything you need is free - plus huge community to support if you ever stuck. All you need to do is Ctrl-Alt-T, apt-cache search ... , apt-get install ... quicker than anything else.