When you surf directly on the phone are you using t-zones? If so, you are using 'wap' which is kwap internet. That was suppose to be a joke. But, if you browse to the same web page on the phone and then the NIT do they perform silimarly and look the same?

On my t-mobile GPRS connection, there is a long 1 to 10 second delay before data starts pooring in and it's the same through my laptop and windows mobile device. The speeds that you are getting are definitely GPS speeds (twice that of dial-up modem). So what you are experiencihng seems normal to me.