Should DSL Line be sugggested

I am currently using two 128 kbps lease line with different ISP’s. I am planning to migrate one 128 kbps into DSL Technology. I am too concern with security, for the DSL ISP will just have to setup a modem/hub without a router? Will I benefit from this setup or not? Can I have the pros and cons of this action? Is there any way I could merge the DSL bandwidth with Lease line bandwidth that they could form a single bandwidth like what others are doing with Lease line bandwidth by using BGP in Cisco Router? How can I protect my LAN from my DSL ISP without a router? I don’t have any firewall either…..

Thanks

Felix