Also, there are often cases where memory on your computer is either non-expandable or already maxed out. I maxed out my laptop with 8 GB and I don't feel like I have memory to waste with the usual office tasks, on Ubuntu. Being conservative and remembering that Ubuntu switched to "recommending" its 64-bit variant as default on its start page less than a year ago, naturally I chose 32-bit the last time I reinstalled the system. But, I'll choose 64-bit next time, because I see mainstream software support shifting to 64-bit for some applications, and because I read up Phoronix tests where 64-bit shows noticeable performance advantage.