dlink 300g help establish reliable internet connection

Hi,

I hope this isn't off topic, as it is my step to connecting wireless, if there
is a more appropriate group let me know and i'll repost there.

I have a dlink 300g+ modem, latest firmware connected to my pc. Here is my saga
:-(

When I boot up the pc all appears fine as I am allocated an IP address from my
ISP of 81.129.x.x, when I try and access web pages, "page cannot be displayed"
appears.

I access the admin page and click on disconnect, let it reconnect and assign a
new ip address, sometimes it will let me view a web page, but when I try to
follow on to a different page it fails "page cannot be displayed". If I repeat
this process a few times, eventually I manage to get a connection that stays
alive, even after a reboot !!! it will reconnect successfully. Occasionally I
have to completely reset the modem and re-enter the login details etc. this
also needs to be repeated to get it to work.

But, when I come back next day .... I have to start the process all over again.

I have replaced cables, micro filters, network card, changed link speed,
disabled firewall, reinstalled operating system (XP pro)

I also have a usb modem which was originally supplied, it ALWAYS works fine
first time when I connect it, but I ultimately want to use a Belkin 54g
wireless router that I have to support the house for internet access without my
pc acting as the gateway.

All help greatly appreciated, my grecian 2000 and hair replacement therapy are
becoming too expensive.

regards

Ian