Can I connect to WiFi with an Arduino, "wireless SD shield" and XBee
The xbee network and the wifi network are both wireless networks, but, they do not communicate with each other.

You have two options. 


Attach a second XBEE to your computer using one of these
https://www.sparkfun.com/products/11812
Get a WIFI shield http://arduino.cc/en/Main/ArduinoWiFiShield