(I've seen this question and some related ones, and perhaps this is a duplicate although part of my question is specific to the Atom D510.)

I'm going to be installing Ubuntu on a new silent desktop as my latest (and hopefully last) attempt to switch from Windows to Linux for at least most everyday tasks. The new machine is entirely passvely cooled, but as a consequence, not astonishingly powerful — an Atom D510 (dual-core, 1.6GHz, HT) on Intel's D510MO board. That's fine, I won't use it for gaming, (much) video editing, etc.

It's a 64-bit processor and I'm maxing the board out at 4GB of RAM (hey, that 1.6 CPU needs all the help it can get), which naturally raises the question of whether to install Ubuntu 64-bit or 32-bit (and if the latter, either live with the missing RAM, or do the PAE kernel dance).

Although I've used Linux on servers for years, I'm very nearly a Linux desktop newbie and am not currently in the mood to fight driver wars and such. So if I'm setting myself up for failure with 64-bit, I'll live with the missing ~0.8GB or fiddle with PAE. But if 64-bit is entirely "ready," great, I'm there.

So:

1. Do most mainstream apps (now) play nicely with 64-bit Linux?
2. I can't help but notice the "AMD" in the ISO image filename ubuntu-10.04-desktop-amd64.iso and I know AMD lead the way on this stuff — does Ubuntu 64-bit play nicely with Intel processors?
3. Just generally, would you recommend one or the other?

(And if anyone has any experience with Ubuntu specifically on the D510 [32-bit or 64-bit] which might lead me one way or t'other, that would be useful.)

Thanks in advance.