request for advice on upgrading

[Reid Priedhorsky <reid@reidster.net>]

Folks,

This post is a request for advice on upgrading my 5-year-old Athlon box,
running Debian testing.

For nearly a decade now, I've been upgrading my hardware piecemeal. When
it was time for a new motherboard, I just took out the old one, plugged in
the new one, fired it up, and it Just Worked. No reinstall required.

But now, the future is clearly 64-bit.

Bottom line: I would like to upgrade with as little pain as possible. I
installed a SATA software RAID not too long ago, and the only components
that need replacement are motherboard, RAM, and CPU. I have been googling
but haven't yet been able to form a coherent strategy.

Can I buy 64-bit (amd64) stuff and just do what I have been doing, i.e.,
drop it in and reboot, keeping my i386 install? If so: What are the
drawbacks? (E.g., performance hit, memory limitations.) Can I eventually
upgrade to an amd64 installation in-place later?

Thanks for any comments, suggestions, or links, and please let me know
if there is more information I should provide.

Reid