I have similar setup in my house ... Bufallo w/ DD-WRT rocks !
Anyway here is a quick glance at my setup in my home
1. Motorola Cable Modem from Comcast
2. Bufallo G54 running DDWRT v 0.23 sp2. This router is broadcasting WPA wifi. I also vlan this router so that it has an isolated vlan port.
3. I use this isolated port above and hook it up to my netgear 614 router broadcasting WEP to support my Tivo S2 and Nintendo DS. (The isolated port on Bufallo caused a secure separation on my local LAN)
4. Have an 8 porter netgear 10/100 switch to wire 7 different rooms in my house.
5. Running my own Windows server 2003 Dhcp & DNS server. Also serves as my local file server
6. Running Windows Vista Ultimate version for windows media center sharing.