[CentOS] xhost: unable to open display

When I put
export DISPLAY="IP address:0.0"    ip address being my windows8 desktop

then
xhost +

I get
xhost: unable to open display "IP:0.0"

when I try
export DISPLAY=":0.0"
I get the same thing.

I have centos6.4 running on a late model Dell Blade
Windows8 Alienware laptop

I checked the xwin firewall setting and it is set to public network 
access (but strangely private network is grayed out)
any ideas

-- 
  
Dan Hyatt