WGR614 should have a DHCP server - there is no need to assign anything manually.
Reset the router to defaults, load fresh firmware, reset again.
Set computers to obtain everything automatically.
If still lo luck, manually enter some known DNS servers values on the router.
When everything works, enable security features (WEP, WPA, etc.)
Generally, unless you HAVE TO be wireless (laptop, etc.), remain wired – safer, faster, less problems
