I use Parallels to create a virtual machine within OSX, and have installed an old copy of Windows XP on it. You can use Windows 7 if you don't have a spare OS and need to buy new. It's great, you basically just have another copy of Firefox running, through the Windows virtual machine, running WEBIRESS. It looks just like it is running under Mac OSX, the only thing which gives it away is the font and max/min buttons etc.
Much better than running bootcamp imo (where you have to pick which OS to run).
