From potato to woody (or sid?)

[Vittorio <vdemart@supereva.it>]

While I'm quite satisfied with my potato 2.2r3 on my laptop, at home
on my celeron desktop I need to install something a bit 'ahead' of
potato (already installed on the desktop!) because I need support for
USB scanner, for that damned i810 motherboard and the Gimp 1.2 and so
on.

I was thinking of woody or sid. 

First question:
What are the main differences between the two distros?
 
Second question:
How should I modify the following two lines in sources.list to use
with dselect? 

deb http://security.debian.org stable/updates main contrib non-free
deb http://ftp.it.debian.org/debian stable main contrib non-free

Or should I use apt-get?

Ciao

Vittorio