Can Ping address but not name

I recently purchased a new router(Belkin). My windows 98
machines run fine, but my XP machine kept giving the
message at the bottom that network is unpugged. It would
still work but very slow. So I changed the network card
in that machine to a Belkin. I uninstalled the old and
installed the new and then couldn't get to the network at
all. It would not get an address from the router. So I
maually put an address on the card. No I can get to the
router but not out to the internet. It won' resolve any
names. I put the DNS setting for att into my XP
machine,but no luck. It will allow me to ping address on
the internet, but it will not resolve a name.