Upgrading from woody to ? sid

[joebosak@uku.co.uk]

I have woody installed but I'm starting to find packages are older than (for 
example) kernel 2.6.9 seems to require.  I'm not sure what to do - do I 
upgrade to sid?  How?  Or is this what 'unstable' is about? 

If I want to use unstable packages, do I just change stable to unstable in 
my sources.lsit and let apt do the rest?