First, reread HF Wang's contribution on this! He's right.
(although ifconfig /a will only work on a NT/2000 box, when using Win9x you should/could use winipcfg to release/request dhcp-leases)
1) In version 4.1.2 or later of the essg, configure the server (from the console) as server and gateway, type dialup. You will be asked which nameserver to forward request to. Use 195.121.1.34 there.
2) Also, consider use dhcp to auto-configure your clients.
3) Try a "nslookup
www.planet.nl" when logged in as root, again when logged in at the console; if that works, and your client doesn't, reconfigure your clients to use the essg as dns-server (shouldn't be necessary when using essg's dhcp features).
Really, retry this, all works well with essg and Planet Internet

Good luck, Bart