myps2 on hard drive –
It does actually run from the hard drive. It takes a 128MB partition (although I have a 256 to store other stuff), the smallest I know how to create on the PS2. As a user partition it shows in the uLE hddmanager as "+MYPS2". I used it for quite a while as it has an internet radio feature, but now I use PS2-Linux and xmms instead. Myps2 was quite advanced for its time. It could network to Windows shared drives (with much troubleshooting effort with line feeds and short capital letters for WINS share name in samba.xml I remember) to play my mp3s when I wasn't listening to the internet radio stations. I liked that I could load winamp.bm style bookmarks, click on the internet radio station, go back to the previous page, and see the artist-title currently playing with a big set of control buttons. ntba2 (the programmer) really did a great job with that and I was sorry to see him leave the scene. Myps2 is great, but with continued support would have been amazing. You'll want version 1.2 from Feb 2006, which is stable.
Other than the internet radio features I still would recommend uLE and SMS. uLE has features which make it "prettier" like the xbox, but I've never really been into skins and button overlays so I can't tell you much about those features. Go to the UlaunchELF forum and you'll find plenty of help and templates/skins to make your filebrowser closer to xbox in style if that is what you want.
If you have any questions about setup, let me know. You got me in a bit of nostalgia to switch out of my ps2-linux/xmms and switch into Myps2 to play internet radio ;-) Still works great!
PS2 v9 NTSC, PS2 v12 NTSC, PS2 v15 VESA