apparently there is some kind of a issue/bug with Vista, where it does not allow you to browse the internet through the LAN where Stateful Packet Inspection (SPI) is enabled on the Router. There are some suggestions on the net which suggest that you disable this on the Router, but this obviously has wide security implications.
Since my Vista would be useles with me unable to browse, i decided to see what work-around options there may be.
When i disabled the ‘password protected sharing’ in the ‘network and sharing center’ my internet connection started working…..
phew…..what a relief
SPI Reference: Ed Bott; A painful Vista networking bug