I really can't answer definitively, but AFAIK the current Core 2 Duo processors (newest members of the Centrino family) are the most efficient.
maybe someone else can chime in on this ignored 2 day old post.
1. Yes, most prebuilt packages have WIFI built in, but if you customize one, make sure to select something that supports your office's protocol (802.11g or 802.11a)
2. Yes, WIFI access points typically have enough power to reach...
If you have an older laptop, Sony has a very good trade-in program going on right now.
$600 credit for any working Sony laptop
$500 credit for any working Dell laptop
$400 credit for any other working...
Just checked on HP.com
It's there, just click the Customize button on the DV2000t series
You can get a Core 2 Duo 1.83GHz + XP Pro + 80GB HDD + 1GB RAM + DL DVDRW Lightscribe + Geforce Go7200 all on the 14" chassis for under $1100USD