Well, I just did 70-351 and I passed with 942.
It was harder than I tought, I was actually very surprised with my score.
Being that there is no official training kit from microsoft and almost no books ou there, I just reviewed stuff from my 70-350 exam. Well I found out I did not study the right things

There was almost only questions about VPN, a little bit of caching and and rules config , etc...
The balance of the different subjects was way off, and many questions where very strangely asked.... Almost feeled like a beta exam !
Anyway, I'm very glad I passed and this just gave me 3 new certs :
MCSE Security
MCSA Security
MCTS ISA2006, Configuring
Yay !
I'm gonna have a few beers tonight !
As always, thanks to TE, and everyone here.