Virtualbox isn’t to bad when I used to use it. I did however at some point stump up the cash for Parallels Desktop. I didn’t really find that this ran the apps any quicker, but it did allow me to use the Windows apps seamlessly with the Mac apps – I can’t recall what the feature is now, but it’s on their current website as seamless integration. Basically you can run the Windows app and it appears “as a Mac window” – i.e it’s in the toolbar and you don’t even know it’s a Windows program, other than the Parallels logo on the app icon. I don’t recall Virtualbox having that feature, so you would have to switch to different desktops.
There’s always the Bootcamp option – though you have to reboot to use Windows apps then.
"Everything looks interesting until you do it. Then you find it’s just another job" - Terry Pratchett