installing to USB

I want to find a version of linux that can be installed to a USB drive and that I will be able to use apt-get on once im done. I think catux would do what I want but I'm having problems getting it to start. Everytime I try to run it stops boot int at "Entering Catux at /dev/sda" usually when i boot to another knoppix my USB key is /dev/sdc I dont know if that is the problem or not, since I am new to linux. If anyone can help with catux or knows of another linux distro that can do what i want it would be appreciated.

Check out CPX.mini -- it's not perfect, and has a few bugs, but it's pretty good. It's got UnionFS enabled by default, so you can use apt-get.

Can't help with Catux because their web pages are mostly in Catalan (?).

By the way: Your system may see your USB key on /dev/sdc when you install Catux (one assumes it's installed from a live CD). But Catux wants to find your USB key on /dev/sda when you boot from it. (If you have some other USB device taking "sda" you may have to disable it. For example, I have an Epson printer with a bunch of card readers and an external USB port that always grabs "sda" if it's on when the computer boots, so I have to turn it off.)

Other considerations include: Does your USB key use USB-ZIP or USB-HDD emulation? Apparently there's a difference in how the geometry is set. And, if it uses GRUB, look to make sure /boot/grub/menu.lst references "sda" and not "sdc".