I went to 64-bit operation with Vista (please, stop laughing) and never looked back. It bugged me that I couldn't ReWire and that both Waves and UA plugs were 32-bit, but I just held tight until they caved and went 64-bit. 32GB of RAM and 64-bit operation is a beautiful thing.
I wonder if the 64-bit angle is why software (not just X2) runs so reliably on my computer.