You can run the 64 bit version of Windows 7. However, since your machine is so new the Boot Camp Assistant is going to advise you to download drivers from the Apple web site. The Snow Leopard install disk that shipped with your machine does not contain all the drivers you need.
If you don't wish to deal with that, I suggest running Windows 7 in a virtual machine instead. (Parallels, Fusion, VirtualBox) Of course that will depend on which Windows applications or games you intend to run.
You'll definitely need to run that FS in natural Windows not a virtual machine. Which means you'll need to use Boot Camp to create a partition on your hard drive and setup a dual boot for you. Take notice of my previous reply regarding the drivers. You'll need that download from Apple or it won't work. And, since your machine is so new, only Vista and Windows 7 are supported. You can not use XP.
Even upgrading the drivers isn't a big deal. I think you will find that once you kick off BootCamp (from within OSX) and read/follow the directions, Win7 will be up and running quicker than if you did a fresh install of Win7 on normal Windows hardware (HP, Dell, Sony for example). I have been running Win7 on my MBP'11 since the first week I got it and have had no issues with drivers or upgrades or updates. It has been cake.
You will be fine running either 64 or 32 bit Windows unless you are running more than 4 GB ram. If you are running more than 4 GB, go with the 64-bit version of Windows.
Not surprising 64 bit version is slow on so old a model. Do away with your partition and try the 32 bit Windows 7 version. Did it not come with two DVD's, one 64 and one 32?
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