Arduino is fast enough for WIFI robot ?

Hello, every body here this my first post.

I would like to build Wireless Robot via WiFi router connect to Ethernet shield and with Arduino Duemilanove.

My project need to control :
4 Stepper motors
4 PWM motors
2 Servo motos
and some of digital input and out put (around 10 ports)

Not much calculation on Arduino chip, control all data will be sent from TCP tunnel via wifi router.

Arduino Duemilanove should be fast enought to control my robot with out any lag ?

if it not fast enough, how could i do ? please advice

Thank in Advance