Need Help in Conf a Cisco 2600 Series Router

Hi everybody
i recently started working on a small network
consisting of the following components

*Cisco Catalyst 2900 X24 Ports
*Dlink Router w/ Wrls capabilites dl-514
*Cable Modem Internet Connection

the hardware was used in an old location where the internet connection was a fiber optic instead of the broadband cable available now(Broadband Connection still have Static IP)

Now
Dlink router is the DHCP server
and all the workstations and Servers are connected to the Cisco switch on the same vlan (vlan 10)
and the dlink router as well to the same vlan-10 ether port 1

however ... we still have a cisco router 2600 series ..pulled from the old network and now not plugged

the old design of the network was as following

1-fiber optic interface connected to the switch on port ether23-vlan 40 thru ethernet cable
2-Wan port on the cisco router connected to the switch on port ether24-vlan 40 as well
3-workstations & servers connected on the rest of the ports vlan 10

i assume the cisco router by then was handling the dhcp and routing bw vlan 10 & vlan 40

how do i configure the cisco router to
1-take care of the broadband cable connection instead of the dlink router and transform the    dlink router to an AP connected to the cisco switch
2-add vpn tunneling and firewall capabilities thru the cisco router ?

do i need to reset the cisco router completly? and how would the new config file look like
and is there any new conf that should be applied on the cisco switch

best regards