Linksys and internet slowdown

Hi-

I administer a small office network that has 2 gateways: one is a DHCP
router from cisco that is also the gateway for a cable modem that has
5 computers using the connection, all using dhcp.

this segment is uplinked to a linksys BEFSR41 using DSL which is at
192.168.1.90 and acts as a gateway for two windows xp machines that
have all their settings manually set. They are using a DNS server on
the other segment of the internal network (as is every machine) at
192.168.1.10. It is a linux BeOS box, I believe.

the users of these two XP machines on the linksys have been
complaining about a slowdown when loading webpages that they didn't
have before- it finds the page, then stops, then keeps going after a
long wait. I'm thinking it's just that dsl is slower, but before this
setup the linksys was on it's own seperate network with these two
machines and they had "no problem."

Does anyone know if this is a problem with the linksys' uplink and how
it works, or something similar? It seems like it has to be a DNS
resolution problem, but even when switching to the provider's DNS,
they still have problems.

Thanks anyone.