Try installing it as second system. You will just need another partition and install win7 64 on it, it then should create a boot-menu for both OS so you can try out stuffs. You have 30 Days to insert and activate it so it shouldnt be illegal to try it that way and dont have to buy it if you experience problems or some other drivers wont work.
I recently changed from W7 32bit to W7 64bit exactly for the same reason, and it actually increased my FPS by ~5-10 in most games. Now I just need to do some overcloncking on my E5200 so that I can get maxed FPS.
Go for it, it certainly won't be slower than 32 bit. Also, the driver issues is just a big myth unless you have some really, really weird parts that are sold in like only one country and the Windows Update searches and downloads most of the drivers you will need automatically, it has some problems with unpopular Chipsets and Audio cards though. I had to manually download drivers for my Realtek HD Audio Card, but that's about it.
I upgraded last night and I must say WOW. This system just seems a lot more responsive overall now. Dolphin is a good deal faster for me now so are a few other emulators.
Thats good
I got just a little faster, maybe 3 fps...
your cpu is a bottleneck for dolphin (yes, so it's mine)