Since HandBrake wasn's written to take advantage of 64 bit addressing, the fact that you're running it on a 64 bit machine makes no difference.
HandBrake, on my slow-ass machine, will usually convert a 2 hour DVD in about 7 hours (that's on an old 100MHz bus, 500MHz machine). On my buddy's dual-1GHz machine, it'll do it in about an hour and a half.
Some DVDs, I've noticed, take longer than others -- I usually get about 11fps, but I'm assuming that some DVDs are a little "tougher" to rip than others, and I've seen it go as low as 6fps on my machine for the entire DVD.
Disclaimer: I only use HandBrake to rip my DVDs to MP4 videos for watching when carrying around a DVD isn't feasible or convenient... just thought I'd add that!