2 Mac Desktop (AirPort Extreme), 2 iBooks (original AirPort and AirPort Extreme), 1 Toshiba notebook (WindowsXP, 802.11g), Wii and PS3 (both are 802.11g)
This was my old setups
Qwest DSL modem -> Linksys WRT54G v3.1 (tried factory and dd-WRT firmwares) + NetGear WG602 v3 (hard wired via CAT5) since WDS didn't actually working. I also purchased the Apple Express, but later sold it.
I did some homework on the Apple AirPort Extreme base station (802.11n) since none of the hardwares were 802.11n ready. I took a bet and decided to get one with educational discount.
It works beautifully right out of the box. Since there is an iBook G3 (802.11b), it will disconnect when other 802.11g clients are using a lot of bandwidth, e.g. buffering youtube video. Days ago, I decided to re-purchased a refurbished AirPort Express from the online Apple Store. WDS over WPA/WPA2 works right away with the much easier and improved AirPort Utility. Now, the iBook G3 is happy. However, my sister's Nintendo DS Lite refused to work since I didn't feel like 'downgrading' to WEP encryption.
The AirDisk is fantastic. I stream ~1700 kbps MPEG-4 (720x400 pixels) video files without any hiccup on my 802.11g Macs.
If Apple sells it for US$149.. that will be a sweet spot IMHO.