linksys befw11s4 v.4 issues

if anyone can help me understand this/these problems i'd appreciate it. i'm convinced it stems from the router, not the internet service itself because it never happens when i'm connected directly to the modem. so here it is. there are times when the connection is fine for a while and then suddenly cuts out. there are times when after i reset both modem and router the connection is alive for 30 seconds and then cuts, repeating like that for more than an hour. there are two windows comps wired to the router and one mac wireless. I have the latest firmware, i'm using wep, on auto speed/duplex, optimized mtu....even filtered out gnutella's ports to save on bandwidth (separate question here...does that last step even make a difference)...yet this keeps happening over and over again. i haven't tested this long enough to see if it matters but i know when i disable the wireless download speeds on the two wired pcs skyrocket...it's the wireless-b router...should i get a g-compatible router, or are there any other ideas...i'd prefer to keep wep on cuz honestly, there are a lot of freeloaders around that frustrated us before it was on...thanks for your help