Comparing the two:
CPU: Sentia offers more and faster options
RAM: Sentia RAM is PC2700 333Mhz, HP uses PC2100 266Mhz, quite a bit slower RAM
HDD: Senta uses ATA and has the hitachi 7200rpm HDD. HP with 4200rpm and slow EIDE interface; Sentia HDD a lot faster.
DVD Writers: The Sentia has an 8x, the HP does not disclose
Wireless; Sentia uses latest Intel (2915); HP uses the old Intel (2200). New Intel provides more variety in connections and is more stable.
Battery Life: The HP needs a special (read BIG) battery to get to the 8 hrs, and only gets there by sacrificing performance big time. The Sentia gets around 4 hours, but they are 4 high performance hours.
Software: The Sentia comes with the OS and the DVD Writer software. This allows you to build your image to your tastes. The HP? Look at the list of "bundled" apps; the image is choked with crapware. You'll need to reimage as soon as you get it, assuming HP provides the actual Windows XP media (which AW does).
Style: HP does not have the eyes....
Screen: The specs for the HP screen sound good. The Sentia is a ClearView WUXGA, and is very similar to Sony's XBrite.
To summarize, the HP may get some more battery life, but the Sentia will literally run rings around it performance wise while still getting excellent battery life.