32 vs. 64 bit Linux

[Harry Giles]

I have a new laptop with a Turion 64 x2 processor.  My questions are:

1.   Is there any noticeable difference in using a 32 bit distro instead 
of 64 bit, performance wise?

2.   If I load on a 32 bit system, and then later load a 64 bit version 
that allows you to preserve /home, will there be any issues?


TIA


Harry G