Moving the server and all the network hardware to the basement was great -- it got it out of my closet -- but that presented a problem for the wireless, because the wireless router wasn't strong enough to get a signal up to the back bedroom on the second floor, where we have a squeezebox and need a steady supply of bits. I have a couple of the cheap Linksys routers (I am always surprised at how useful it turns out to have various extra computer parts lying around.) Unfortunately, the Linksys firmware doesn't do what I wanted -- which was to have one box do the gateway router stuff (NAT, DHCP, etc) and another act as a wireless access point. They want you to buy the more expensive Access Point version of the box, which is identical except for the firmware.
So, I installed the DD-WRT firmware on one of my Linksys routers, which lets it act as an access point -- among many other things. DD-WRT is a linux-based distribution for cheap hardware routers, which includes all sorts of networing software not supported by the out-of-the-box firmware (e.g., access point and access point client modes, ipv6, VPN, WPA (client and server), port forwarding, QoS management, SNMP, DMZ, etc.)
As often happens, the road was bumpy but in the end everything worked fine. There are half a dozen different versions of the popular WRTG54, so the instructions might not fit your version exactly. (I learned this on the part where it says "pull firmly to remove the bezel", and my version had screws holding the circuit board to the bezel...and pulling firmly ripped them out.) Despite following all the directions carefully, the first flashing attempt failed, and I had "bricked" my router. I followed the various "debricking" instructions, and eventually had to resort to the most extreme, where you have to short a few pins on the flash chip to restore it to its default state...and eventually I got WRT downloaded into the box. From there, it was smooth sailing, the web-based admin GUI was easy.
Once I had DD-WRT running, it was easy to configure it as an access point -- and if I need better coverage, can just add more. Also, a cheap router + DD-WRT is the cheapest way to put a wired ethernet device onto a wireless network; run it in "access point client" mode. Much cheaper than buying a device designed for this purpose...