since everything worked for more than a year until you added an older laptop, that laptop is the culprit. its probably throwing some sort of interference and replacing the router won't stop the interference. if the suspect laptop uses 802.11b while everyone else is 802.11g, then that could the issue. some routers don't handle mixed-mode well.
i suggest you delete all of your wireless network connections on all laptops. then reconfigure the router for wpa2, reconnect your original laptops and get them working again. then add the older laptop. if it causes the same problems turn off its built-in wireless and get a new wireless g card for it.
I want to know if I should keep my current router WGR614v6 as it is showing problems as posted on this thread: http://forums.cnet.com/5208-4_102-0.html?threadID=339861%20&tag=unsubscribeForm;tracked-disc
Should I get the Linksys WRT54G2: http://reviews.cnet.com/routers/linksys-wireless-g-broadband/4505-3319_7-32937120.html?tag=mncol;lst
or any other routers that are least known to disconnect internet.
I know about the n routers but all my computers are all g and I am not going to waste to change all the computers, around 5. So please don't say anything about the N routers. Just keep it with the G routers.
The only thing I'm asking because I've seen that every router almost has the same problem of disconnecting but if I get a new one, I might get the other laptop back onto the internet.