I am not familiar with multibeast and stuff like that, as I have the opinion that applying patches to OS X by yourself is usually the best way of having a hackintosh done.
To prevent missunderstandings, I think I should try to explain a little more... As you are on quite compatible hardware it's reasonable for you to use Vanilla instead of Legacy Kernel - this is giving you more options like the possibitly to enable Intel Speedstep, etc.
Note that even with using a Legacy Kernel you do not need to use the -force64 bootflag - this Kernel mode is designed for use with AMD and older (pre-Core-Architecture) Intel CPUs lacking some SSSE3 instructions necessary for 64-Bit support.
For use with 10.6.3 get 10.3.1 Vanilla Kernel here. Be aware that this Kernel has no Powermanagment Disabler patch (as it's unpatched ), so you should check if NullCPUPowermanagment.kext or similiar is beeing loaded on your system. To replace it move the old Kernel by "sudo mv /mach_kernel /bak_kernel" on Terminal and copy the mach_kernel from the archive directly to your OS X partition. On next boot up check if you are running Darwin 10.3.1 using "uname -v" on Terminal.
If you take a look into System-Profiler/Software you might notice that it will say that you are not running 64-Bit Kernel - this does not mean that applications cannot access 64-bit memory range, as you can see in activity monitor - if you want to you can boot into 64-Bit Kernel using bootflag depending on your bootloader, commonly this is arch=x86_64 on Chameleon and most of it's forks, but keep in mind that this requires all your Kernel Extensions (kext) to be 64-Bit capable...

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