I do believe that there is at least one netbook already using an ARM based CPU, the NPX-9000. It is apparently the lowest cost netbook in production. http://en.wikipedia.org/wiki/Comparison_of_netbooks
Found it on that list.
Third rig: PC Express Invader. C2D E6400 2.13GHz, 4GB DDR2-800, 320GB HDD, Intel 945, Asus 9600GT 512MB, 550W PSU, W7 HP 64-bit.
Fourth Rig: Dell Optiplex 170L, P4 Prescott 2.8GHz, 512MB DDR266RAM, 80GB HDD, FX5200PCI 128MB, 250W PSU,XP Pro
Fifth rig (Laptop): Dell Inspiron 4000, 14.1", PIII 850MHz, 384MB RAM, 9.3GB, XP Pro. Now with passive cooling!
“I could make a better looking computer case with a bucket of Lincoln Logs.” -lemode