While I had previously considered wiring our new old house for ethernet, after consulting with an electrician I decided to postpone the effort. We simply lack enough access to the walls to do it as clean as I would like it.
Thankfully, wireless reception throughout the house is excellent. Wifi should have been my first choice, all things considered. I got a new Airport Extreme base station, an AE card for L's G4 iMac, and a D-Link DWL-122 USB wireless "adapter" for the new TiVo. And I installed a phone jack in the basement, all by myself (damned easy).
We already had an older Airport, but I sprung for the Extreme (802.11g) model in the hopes of getting extra-fast local network access and the ability to connect a USB printer to the wireless network. Sadly, Brother printers don't play well with the Airport Extreme (or is it the other way around?). The iFelix unofficial Airport Extreme and Express Printer Compatibility List doesn't mention the older HL-1240 explicitly, but the HL-1440 is known to have problems. Brother suggests pretending it's an IP printer (not a Rendezvous printer), but that doesn't appear to work. This page recommends downgrading the Airport firmware, which makes me sad.
I otherwise very much love my Brother HL-1240. Brother was one of the first to make inexpensive laser printers (Amazon sells the 1440 for $89 after rebate), and I've never had a problem until now. Given the unusual nature of the AE printer compatibility list, I blame Apple, not Brother, but I really don't know anything about it. I hope Apple is willing to fix the problem.
P.S. If you're looking to get an Airport card for your "G4 iMacs" (aka "flat-screen", or lamp-style), take note: Older models only take the original 802.11b (non-Extreme) Airport cards, and not the new 802.11g (Extreme) cards. You know you have a new one if a) you have a 1GHz processor, and/or b) you have USB 2.0 ports. The older cards are no longer sold by Apple, but some stores still have them at a premium price. I ordered one from an eBay seller after a "genius" at the Apple Store neglected to mention criterion a), convincing me we had an older iMac, so if you need one right now, I can hook you up for cheaper than retail.
P.P.S. Prior to ordering the Airport card, I tried using the D-Link DWL-122 USB wifi adapter with the iMac. The v1.0 drivers didn't work at all, and the latest drivers from the D-Link website worked but crashed the computer every few minutes. Isolated circumstance, maybe, but it wasn't fun. (OS X 10.3.6.)
And in case it wasn't clear: The new Airport cards don't work with the old G4 iMacs, and the *old* cards don't work with the *new* G4 iMacs.