Charles,
I agree with Scuzi, WinXP Pro will work fine for what she is looking to do.
If you do end up going WiFi, do get an 802.11g Router. I would look at getting the same brand for both the Router and NICs, since USRobotics and Netgear only give the real boost in throughput when you use their Router/NIC together.
Take Care,
Richard
P.S. SATA and IDE will give you the same speed on the Server, unless you use a 10,000rpm WD Raptor Drive.
