Yes a Cisco router can do all those things and more. Plus it is a dedicated piece of commercial-grade hardware - no matter how good your Linux router may be, chances are it'll be running on a standard PC architecture motherboard with a cheapo single power supply etc. Plus you've got support from Cisco but if you do the job yourself you're on your own. In summary, if you're doing the job for a commercial company then I'd do it properly.
What type of client is this for? I agree with superudu, a dedicated Cisco router would probably be best. With that being said though, not all Cisco equipment has redundant power supplies and buying support from Cisco if the router isn't straight out of the box isn't cheap. Check out the pfSense project, its a good project. If you are going with the Linux Router option as opposed to the Cisco Router option be sure to explain to the client the pro's and con's of each, ultimately it will be them paying for the support and associated maintenance. Good luck!
