I use Windows 7 x64 but for security analysis I use BackTrack 5 R3.
Normally, VMWare is better (in my eyes) mostly because it has so many features such as Snapshot, other unique features which not only makes Development simpler but for Testing, it eases by debugging.
All in all, VMWare is better than dual-booting.
I dualboot Fedora 19 and Windows 7. Majority of the time I'm on Fedora. There's not any Windows-only software that I use. I don't play video games (partly because my graphics card is total crap). Linux is just easier for me at this point.
I dual-boot because I play video games on Windows but I don't like programming on Windows, so I use Linux for that instead. Sometimes I also use Linux for general browsing because it has better media players, like banshee.
Having said that, it doesn't work on Arch Linux either at the moment, though that may just be a problem with my setup.
I do play games, but I don't have windows any-more. I've found that Wine works really well for anything that is windows-specific. I haven't tried too many graphics intensive games, but I play a lot of Diablo 3 with Wine.
I'm zapping this thread back because I just found another reason for dual-booting.
I run Mint with the Cinnamon DE by default. When I want to use 3 monitors I switch to MATE and restart X. When I want to program, I switch to xmonad and restart X. The other day I wanted to try wm-i3 instead of xmonad. When I installed it (apt-get install wmi3) MATE was un-installed! I like wmi3, but can't figure out how to have it installed at the same time as MATE. Therefore I'm going to dual-boot with ArchLinux/wmi3.