hi. really torn between the two. unfortunately do not have much experience with handhelds. the reviews are quite similar for both, although i am not quite clear on the memory differences mentioned in the reviews and what they mean (RAM, ROM, "available RAM").
for example, the hp has 56MB of available RAM, and the dell seems to have only 30, the dell has 64MB of ROM, but there is no mention of ROM for the hp. etc
need it primarily for organizer/email/word/voice memo. screen clarity is very important. secondarily, for audio playback/record. other features such as picture viewer are a bonus. do not intend to replace for a few years, capacity to keep up with new programs/functions, reliability/service are considerations.
the hp is more expensive but has more software, although some reviews did not glow about the media applications. all in all the reviews seemed to give a slight edge to hp for display, battery life, sound, gaming, features.
The rx3115 does have a sharper and brighter display as well as more memory. The procesor using in the HP does a good job of handling multimedia tasks and image viewing. For the things you listed, I'd suggest the HP.