Small business wifi router for voip and LAN traffic

Hey all,

I'm currently using a Time Capsule to network a small business, but we're bringing in another VOIP line and I'm wondering whether I might need something a little more heavy duty. Essentially what the business needs is something that can handle:

-Two separate VOIP lines, being used simultaneously at times

-3-4 computers talking to each other over LAN (afp), exchanging the occasional file and backing up to the TC (I've restricted this to non-business hours because it can really choke things up)

We've got a 10mbps cable connection and I'm pretty sure that's enough. Also the TC has pretty poor wireless range and we've been forced to use devolo ethernet-over-power line adaptors. So far we haven't had too many quality issues with VOIP but I'm afraid that the router may become a bottleneck if there's to much LAN and WAN traffic.

Any ideas what sort of wifi router would fit the bill?

Thanks in advance