Adding Belkin Router slows network

Hi All,
Been battling this for several months including 10! calls to belkin........
Configuration is:
4 WIN98se machines via Ethernet 10 base hub to Speedstream ADSL router.
Everything fine altho moving graphics and music concurrently creates
conflicts. NBD
BUT, when replacing the hub with a Belkin Wireless Router (4 ports),
Internet access speeds drop dramatically. Often pages will just time
out without loading. This is for PCs connected via CAT 5 to the router;
No wireless in play. Acts like a DNS issue but is even slow when IP
address is used. Have disabled DHCP on the ADSl but NG. Disabled DHCP
on Belkin and NG.

Any ideas where to begin looking???

Cheers,

ZZ