KONY - I was at the range, shooting my P99!!
The P99's that CDNN carries are the 2003 models. They have a proprietary rail that requires an adapter to mount Surefire or other popular styles of lights. The QA model that CDNN carries for $399 has a Glock/Steyr-like trigger action -- precocked striker with consistent trigger pull. It also has a decocker, which can render the pistol useless if it's used because there's no second-strike/DA capability. I think the one they're selling for $429 is the traditional DA/SA (now called the P99 AS) -- but you might want to confirm it with them. I wanted a 2004 AS model, so I ended up paying significantly more (around $600).
I love my Steyr alot -- but the only gun I have that I won't part with is my P99. For me, it's consistently the smoothest, most accurate and most comfortable shooter I have. I did just have it at the range tonight and put another 250 flawless rounds down range. I'm using it as my CCW piece in a Comp-Tac C-T.A.C. holster. My M9 is going to be my second carry gun...I'll probably end up with a C-T.A.C. for it, too.
It's really hard to beat the value of the M9. If you go with CDNN, then either gun will require a rail adapter. Magazines for the Steyr are cheaper ($29 vs $39) but the capacity is less (14 rds vs. 16 rds). There are more options for replacement sights (tritium night sights or fiber optic) for the Walther -- but the trap sights on the Steyr are great for rapid acquisition in "combat-like" conditions.
Bottom line: you'll be pleased with either pistol. If money is a concern, go with the Steyr. If you don't mind spending the extra money, buy the Walther and save up for the Steyr as your next piece.
I have some pics of the guns and some of the target results on my web site, here:
http://users.adelphia.net/~navy87guy/index.html
Hope this helps!
Jim