Hub for internet access.

I inherited a small network to distribute T-1 internet access (recently changed to wireless), and it has never worked properly. The internet feed goes into two Cisco 2610 devices, and out to 32 different PC’s. Some PC’s can connect to the internetall day every day, some can connect only during times when nobody else is on the network, some cannot connect at all. Does this look familiar to anyone? What other info do I need to supply?