Looking for a simple guestbook solution

[bydesign]

I'm looking for the simplest no-nonsense guest book and wonder if there are any I can place within a page on my website without huge amounts of faffing on (I'd much prefer the guestbook to remain within the website rather than going off to another URL).

This is what my client wants me to replicate on her website…
http://ladiesofletters.squarespace.com/your-views/

and any ideas / pointers are extremely welcome