[Cooker] 64 vs 32 bit Cooker

[Robert Fox]

Up until recently, I have only been using 32 bit Mandriva (Cooker) -
although I have an AMD 4200+ X2 based machine.

Now I just got a new notebook with Intel Core Duo 2 and tried for fun
the Mandriva 2007 DVD install - there was no choice given, it simply
installed X86_64.

Two questions:  

1)  Shouldn't the install ask which version (64 or 32) to install when a
64bit processor is detected?

2)  I read somewhere that there is little advantage to 64bit Linux for
desktop.  I also recall some problems with OpenOffice and Firefox
plugins.  How up to date is the X86_64 side and what in known not to
work?  In other words, can someone spell out what the advantages and
disadvantages of using 64bit OS vs 32bit (from Mandriva perspective!)

Many thanks in advance for your replies.

R.Fox