-64bit Ubuntu or 32bit?

Hi All-
I just got an HP slimline with an AMD 4000+ on sale. The motherboard
has room for 2gb max of ram (which I bought with the order). Which
Ubuntu ??

* I will run primarily Postgres 8.2x, PostGIS, Perl and Python, along
with a specialty program called GDAL. I will have some decent sized
DBs loading and searching. (to me thats, hm, 1.8m records in a simple
flat table as the largest so far. Other large'sh tables in the same
DB)

* I configured another Ubuntu box for work, which has more RAM and I
went with the 64bit. I want to synch files between these two as much
as possible. Including DBs.

* I will run the new one headless, but with the full desktop install,
using Remote Desktop/VNC occasionally

* I build apps from source, install python and perl modules to write
against, and other modest hacking

* My Linux experience is LOW, though I am a programmer

thanks for any tips
-Brian
.