function createSniffer()

            {

                this.agent  = navigator.userAgent.toLowerCase();

                this.major  = parseInt(navigator.appVersion);



                if     ((this.agent.indexOf('mozilla')!=-1) && ((this.agent.indexOf('spoofer')==-1) && (this.agent.indexOf('compatible') == -1))) this.browser = 'ns';

                else if((this.agent.indexOf("msie")  != -1))  this.browser = 'ie';

                else if((this.agent.indexOf("opera") != -1))  this.browser = 'op';

                this.ver4=(this.major>=4);



                if     (this.agent.indexOf("win")!=-1) this.os='win';

                else if(this.agent.indexOf("mac")!=-1) this.os='mac';

                else if(this.agent.indexOf("x11")!=-1) this.os='x11';



                else                                   this.os='unknown';



                if(this.browser=='ie')

                {

                    this.pageW = screen.width;

                    this.pageH = screen.height;

                    this.pageX = 0;

                    this.pageY = 0;

                }

                else

                {

                    this.pageW = screen.width;

                    this.pageH = screen.height;

                    this.pageX = window.pageXOffset;

                    this.pageY = window.pageYOffset;

                }

                this.res = (this.pageW<=800)?1:(this.pageW<=1100)?2:3;

            }

            var sniff = new createSniffer();