I bought the 1 Gb U2 for myself; works like a charm. The only downside? Firmware upgrades have to be installed in Windows. Other than that, it handles my Ogg files (q7) no problem. It's truly a drag-and-drop operation. In fact, I like iAudio so much, I'm waiting for the successor to the M3, and I'm going to buy one of those (FLAC support)
I've done what many others have done--encode my CDs in FLAC for listening at the computer, and then lower-quality OGG for my portable players.