After battling these wireless routers for years, I've finally found a configuration that is very stable.

1. DSL modem
My version can hold public IP address and DNS addresses. Since these are assigned by the ISP (AT&T), they are responsible if any of these don't work.
2. Router
This is a Linksys WRTP54G with the wireless function turned off. WAN port is set to "obtain IP address automatically". The only function this box does is DHCP address assignment, be the network gateway and top level network switch. This is also the Vonage VoIP box.
3. Wireless Access Point
This is a wireless router set to act as an access point. The WAN port is not used and DHCP is turned off. I practically change this box every year due to technology changes. The latest is an Airlink 802.11n that only cost $30.

Since functions are spread across several boxes, heat is also spread across several boxes and each box is much cooler. The hottest box being the wireless box but I change it whenever something new comes along way before it has a chance to fail.

In actuality these routers all use chipsets from Broadcom, Marvell, Atheros and Ralink. It really doesn't matter what brand the box carries. Reliability depends more on the chips inside.