So I have a external usb-hd with my files. It's formatted as ext3, all of the files were written to it from ubuntu were I had uid:1000 and gid:1000. Now I'm on fedora where I have uid:500 and gid:500. The removable-device-automount thing mounts the drive with drwxr-xr-x for 1000:1000. But most files are only readable for uid:1000, not even for the group 1000. But anyway, I would like to write to it without causing a mess. I might move back to ubuntu in a month or so, so I don't want to pillage and plunder, I want to solve this like a big boy.
I know I'm missing something obvious.

---edit---
All the files can be changed to have the same access permission. So chown-ing them all would be an option

the way I see it, you can:

(1) use the find command to change the UID & GID on the USB files

(2) change your user's UID & GID on Fedora from 500 to 1000 (or vice versa on Ubuntu). Then do #1 on the local system changing all files with UID/GID of 500 to 1000 (so your user can still access them -- like files in your user's home directory).

(3) expand group's permissions on the USB files; add a group on the Fedora machine with ID 1000 and put users with UIDs 500 & 1000 into that group.

Other options probably exist.