I have 8GB of RAM and was wondering if I'd gain an advantage if I were to run my Mac in the 64 Bit kernel?
No, but I have a similar configuration and recommend 64 bit for a couple reasons:
o It's a little faster. Intel licenses x86-64 technology from AMD, and it's slightly more efficient in execution than 32-bit.
o It's slightly safer. Though barely a concern under OS X, much Windows malware is written for 32 bit.
o In my experience, it's slightly more robust. I run a lot of virtual machines, and VMWare Fusion under 64 bit OS X has seemed both a little faster and a little more solid in really abusive use than under 32 bit OS X.
There may be some software floating around still that is not compatible with 64 bit mode, but you can always restart in 32-bit if you need to. (Just hold down the 3 and 2 keys while booting.)
(I'm sure we'll have some respondents saying that 8GB can be accessed in a 32 bit OS X system, and they are correct. It is also correct that 32-bit OS X will run well-written software in 64-bit mode.)