to CF
OK, dooing some googling on Draytek 2600 suggests you've got a ADSL connection rather than Broadband. I'm not convinced that putting a Broadband router (cisco 806) on to an ADSL modem will work - the Cisco expects to be talking to a CM on an ADSL modem. However, if you want to try it, have a look at
http://www.adslguide.org.uk/reviews/ which has a number of Ethernet ADSL modem reviews.
However, the D-Link DSL-300T on ebuyer costs £39, which is barely less than an combined ADSL modem/router/firewall device (eg Linksys AG241 at £44)!
Personally, I would ebay the Cisco and get the Linksys all in one!
HTH