Linksys WMP54GS Question - Security and weak signal

[Biopsychosocial]

Howdy ya'll. i setup this wireless network @ home and two towers use the card and the one between the two hosts the router. Mine accesses the router from an apartment outdoors. Yesterday i had strong signal strength, today it's reporting 'weak'.
What could cause this? I just joined the network yesterday with this computer and it was fine. Literally overnight everything went awry. Right now im using the WMP54GS and some linksys router. Is there some kind of motherboard/router/wireless card update i haven't thought of? Outside interference? i haven't figured out how to secure the network yet which is immediately following this on my "to do" list so if you know about that i'd appreciate the help.

[gandolf]

Users with XP Service Pack 2 are the only ones experiencing this problem of dropping a wireless connection with fast access DSL. We did a controlled test where we had a laptop running SP1 and it connected wirelessly just fine every time. We upgraded the laptop to SP2 and it could not even connect to the linksys router (wrt54gs) another one just lost connections and dropped them and could not open hotmail and yahoo email. Changing the router settings from DHCP connection to PPoe and changing the MTU setting from automatic to manual set at 1492, reboot and it works like a champ every time and can now also open emails. P.S. Although always a good idea, upgrading to the latest firmware did nothing.