[ltp] Should I use 64-bit or 32-bit for my new Thinkpads?

[David A. Desrosiers]

I recently ordered a new T61p and an X61s with all the extra goodies 
to replace my ageing 15.1" T42p that has been my "tank" for the last 
2+ years. I need something for development and an ultralight for quick 
on-the-road trips to clients and various offices.

I also added the 9-cell battery for the T61p, but stayed with the 
standard 4-cell battery on the X61s (for now). I'm used to sub-2-hour 
laptop life on a single battery, so anything more than that will just 
be a bonus for me.

My intent is to continue run Linux on the T61p. This will fully 
replace my existing T42p (currently running Ubuntu Hardy Heron + 
2.6.25-rc1). This will be my main development machine. The primary 
drive in the T61p is a 320gb SATA drive.

My T42p has 2gb of RAM, a 100gb primary drive and a 60gb secondary 
drive in the UltraBay bay.

The X61s will be running Windows XP Professional (not Vista), and I 
may end up dual-booting it between XP and Linux at some point. I'm 
undecided on this as yet. If I can recycle the 100gb drive from my 
T42p into the X61s, that would help make more room for both systems.

The combination of these two laptops together will still be lighter 
than my existing T42p (8-9 pounds, not including the second 9-cell 
battery + heavy power brick), which means I can still carry them both 
with me and lose some weight in my "day bag".

I've been doing some reading on the various configurations and issues 
with these two machines, and I have no doubt I'll be able to get 
everything working flawlessly with their intended operating systems 
(sound, suspend, hotkeys and so on). I've been able to tweak and patch 
previous Thinkpad configurations for years to work around the various 
"showstopper" bugs before without too much trouble.

Now down to the real question:

Should I install a 64-bit Linux on the T61p, or stick with a 32-bit 
Linux? I'm not sure a 64-bit version of Linux would really give me any 
benefits, and it would certainly limit what software I can run by a 
fairly significant amount (the Adobe Flash plugin for Firefox being 
one good example).

Has anyone done an analysis using 32-bit vs. 64-bit Linux on this 
hardware?

Any other major gotchas I should consider before I receive these 
machines?