Turion 64 Inside Story on MobilityGuru
According to the table, there are some power settings that can keep you at 800 MHz all the time.
You didn't really give enough information in your posted question...
What power setting do you have the laptop set to?
Athlon 64 3400+ (CG) @ 2.4GHz, Asus K8N-E Deluxe, 2 GB OCZ DDR400, BFG nVidia 6800OC 128MB, Seagate 200GB PATA, Seagate 160GB PATA, Dual Boot XP and x64, Antec 350W Mid-Tower
Athlon 64 3400+ (E3) @ 2.4GHz, Asus K8N-E Deluxe, 2 GB OCZ DDR400, eVGA nVidia 6800 128MB, Seagate 320GB SATA, Vista x64, Antec 350W Mid-Tower