Since I installed Leopard, I've been having network drops (for all computers). Could it be Leopard? I guess it's my ISP, but I have no idea. DHCP server is set up right, but I did see an error where the Mac would complain about having the same address as the router (which is impossible since the POS Linksys is handing out addresses way beyond its own. And I haven't seen that error since today.
And it was working before yesterday, before I installed Leopard.