Differring PR on same pages

[oast]

The front page of one of my sites has a G. PR of 5, but when I type the URL without the "www" prefix the PR drops to 2!

Even worse, one of the main landing pages inside drops from PR5 to PR0 without the "www"

My questions are:

1. How do I get G. to see both forms of the URL as one?
2. Should I get G. to see them both as one?
3. Does it make any difference?

My initial thought:
Use mod_rewrite to 'redirect' all links without a "www" to the 'full' URL (or the other way round - i.e. remove the "www").

Doubt:
If I did an 'Error 301 permanent redirect' to the non-www writing of the domain, will the higher PR from the "www" version be transfered with it?


I hope that makes sense... it's so much easier saying some things rather than writing them!

Thanks
Steve