I just became the proud owner of a iriver h120 rockboxed unit myself.
Thank you very much, thank you.
and thank you Flintstone.
If you're going to get an h120, do yourself a favor and pickup a pre amp/battery box as well since the preamps in the unit aren't that great (such as many recorders) and most mics used with it probably can't power it well enough. I must say that the rockbox community is wonderful and if you ever have questions about any features of the RockBox, you can hop on the IRC and they will help you out. I originally started "taping" (not music by any means) on a minidisc recorder so coming from that to this is highly customizable, like the fonts, how long the blacklight stays on, how long of a pre-record buffer to have, etc.
Pick one up, you won't be let down.