Pinging over home LAN between XP and 98

Hi all,

I have a home LAN that has a latop with XP Pro installed and a desktop with
Win 98 installed.

When I ping from the laptop to the desktop (via router) I get 1ms pings.

When I ping from the desktop to the laptop (via router) I get <10ms pings.

When I play quake from laptop with desktop as server I get a ping of 0ms.

When I play quake from desktop with laptop as server I get a ping of 15ms.

I don't expect a ping of 15ms for quake3 on my home LAN so can anyone point
me in the right direction as to how to diagnose what's wrong with desktop to
laptop ping?

Incidentally, I get a 1ms ping from desktop to router.

Thanks in advance for any help.

Regards,

Paul.