The idea was to install an open source 64 bit OS on my laptop so I could get access to all my installed 4GB RAM.
Tried OpenSUSE 64 and Ubuntu 64.
I found that OpenSUSE did not directly support my laptop graphics card (ATI 3470) so reverted to Ubuntu 64.
Well after several days attempting to get ubuntu 64 working, I decided to revert back to 32 bit version. Ubuntu installed without issues but it was all the other apps that gave me issues (particularly Lotus Notes 8.5).
My conclusion was to revert back to 32 bit and go from there because Ubuntu DOES support the ATI graphics card.
As a side issue, I also noticed that if you upgrade ubuntu 8.10 to 9.04 then suspend and hibernate do not work on my T400 but if you do a fresh install of 9.04 then suspend and hibernate DO work! - cool.
(OpenSUSE ALSO supported suspend and hibernate on my laptop)
To add spice to the mix I decided to use Ext4 file system instead of Ext3.
I must say that I can definately see a difference. OpenOffice loads incredibly fast now.