Virtual Machines are not made for gaming. All the hardware is virtual, meaning that it is no even close to as powerful as the native hardware. While I've gotten a few games to run in VMWare Fusion, they never run at full speed. While the newest versions of Fusion and Parallels have enhanced graphical support, I am not sure if they will be able to game any better. Most of the enhancements have been to enable full support for Windows 7 and all its fancy graphical "stuff".
Crossover Games is good for a handful of gaming applications. It will use the native hardware to run the game, so its your best bet for playing most modern games. It all depends on what you want to play. Check the compatibility section of Codeweaver's website to see what games will work. Since you are running a MB, I wouldn't expect to run anything too powerful (or anything cranked up to High on graphics). The only thing about it that sucks is you need to buy a "subscription" to the software every year to continue getting updates. Originally, I wasn't keen on spending $40 a year to play a handful of games, but I lucked out with last year's Lame Duck giveaway (gave out all Crossover versions for free) and feel in love with it. I lucked out that most of the games I play (Guild Wars, Megaten: Imagine) were fully compatible with CrossOver Games
BootCamp is still the best way to game on a Mac. I understand you not wanting to reboot every time you want to play something, but its the only way to play the latest and greatest.
PS If you do end up getting Crossover Games, I would recommend getting it soon. CodeWeaver us running a "Its not free" sale ATM which give a 50% discount on (I believe) all CrossOver versions.
