I am using Windows XP and I want to install Ubuntu 10.04 LTS Lucid Lynx on my 16 GB pen drive. I have a live Ubuntu disc. I want my install to be persistent so that whatever changes I make are preserved. I do not want to alter my MBR but I want to able to boot fro my pen drive through BIOS.
It works. I use a Jaunty install on a 16GB drive.
Ubuntu Wiki: LiveUsbPendrivePersistent
Update: I completed one 8GB flash drive install of Lucid yesterday.
Of course, BACKUP, BACKUP and BACKUP first and foremost !!!!
I installed Ubuntu Lucid Lynx on a 16GB memory stick with no major issue. However, there is ONE thing that you need to be extremely careful about. At the very last window before confirming and going ahead, you need to click on the advanced button, to change the location of the master boot record for the startup. By default, it will install itself on /dev/sda, or /dev/hda, depending on your hard disk. This is your main booting hard disk, and it will screw up your hard disk. Make sure it is instead installed on the USB stick device, which should be something /dev/sdb, or /dev/sdc.
I would also recommend that you have NO other USB storage device on your computer at that time, and if you can temporarily disconnect your hard disk, it is even safer.
I screwed up two hard disks with this, once with JoliCloud, and once with Ubuntu 10.04.
I would also recommend that you have no swap partition. Such partition is accessed a lot and your memory stick has a finite number of writes it can sustain before becoming defective. If this is only to experiment with Ubuntu before doing the big move, don't worry. If you want to have it permanently on the stick for portable use, remove the swap partition, expanding the main partition instead.
But otherwise, it works like a charm.
If your BIOS supports disabling and enabling SATA and IDE ports, you don't have to worry about accidently overwriting your current MBR. Just disable them first.