Cisco Linksys Model WRT160N V2 - Sporadic Internet Connectivity?

Here's my situation.I had an 8 year old desktop computer that I just replaced with a brand new one (Lenovo). Prior to replacing it, I assumed the slowness and occasional inability to connect to the internet were caused by the computer being so old. But once I replaced the computer I still had problems - in fact it was worse.

At that point I was reminded that the modem was also 8 years old so I had the cable company replace it (Scientific Atlantic Model DPC2203C). The connection improved for a few days but then it went right back to how it was.

I have a wireless router (Cisco Linksys Model WRT160N V2), which is hooked up properly. When I got the new modem I had to reset the router. My wife's laptop now sometimes has connection problems which it never had before, and on my (work) laptop I can access the wireless connection but not through the same entryway that I had before. I'm providing this information because I think it may be relevant. It seems like something has to be up with the wireless router since I reset it. Another thought is that possibly the problem is with one of the wires between the router and either the modem or the computer - not sure if the sporadic connection problems is an indicator of that.