When you download handcent sms is there a way to make it so that your texts go only there and not both sms and messages?
No, But you can disable the stock app from notifying you.
A gun in the hand is better than a cop on the phone.
Only the Skilled Survive
A computer lets you make more mistakes faster than any invention in human history - with the possible exceptions of handguns and tequila.
Drill Sergeant Frick's Rules For Un-armed Combat.
1. Never be unarmed.
2. See Rule #1
USMC rule # 23 of gunfighting: Be polite, be professional, but have a plan to kill everyone you meet.
I don't think you actually deactive the stock messenger. I use Handcent and I just went into the settings for the stock messenger and turned off all notifications. I also removed the shortcut from my home screen. I placed Handcent on my home screen and activated its notifications so those are the only ones I see.