Can i temporarily use Linux on a computer by having a portable version of it on a USB device?

Puppy Linux will load into the RAM of your computer to run faster, if that's what you're aiming for. Check out Pendrivelinux.com. It has instructions on setting up live USB drive installs of all types of distros, all different ways. But if you want to keep it simple, here's the link to the Universal USB Installer, which is a program that will let you choose a distro, like Puppy, and then it will download it for you and automatically set up the usb drive for you. http://www.pendrivelinux.com/universal-usb-installer-easy-as-1-2-3/ Just make sure you choose the right drive, so it doesn't erase your hard drive, of course! I've used this tool many times and it takes a lot of time out of setting up live installs.

Don't know about a hard drive, but i have used it with a cd. I just created a live cd of linux (bootable). Then, i inserted it into my cd drive and it came with options to install or run without installing. I used it without installing, and it worked fine. I think, it will work the same way as in the cd. You just need to create a bootable partition of that drive.

you can boot linux off a cd or usb just make sure your bios is set to boot from disc a good one to start with is ubuntu,or linux mint8 an even better one is puppy linux4.3 that one loads to ram you can save a small file to hard disc that will save your settings

Installing Ubuntu as a dual-boot with Windows without partitioning (XP and Vista) https://help.ubuntu.com/community/Wubi You keep Windows as it is, Wubi only adds an extra option to boot into Ubuntu. Wubi does not require you to modify the partitions of your PC, or to use a different bootloader, and does not install special drivers. It works just like any other application. Wubi keeps most of the files in one folder, and if you do not like it, you can simply uninstall it as any other application. Boot in to windows insert the Ubuntu 9.10 LiveCD and you will offered the option of installing inside windows which is where the Wubi installer comes in, you will be asked how many gigabytes you wish to allocate to Ubuntu (I recommend 8gb) then you set a password for your installation then click install and thats it. Once Ubuntu is fully installed upon starting your PC you will be given a choice of which operating system you want to use Windows or Ubuntu Ubuntu 9.10 Download http://www.ubuntu.com/getubuntu/download Ubuntu 9.10 (Karmic Koala) User Guide http://ubuntuguide.org/wiki/Ubuntu:Karmic Linux Mint 7 has a similar feature called mint4win and the directions given above for Wubi can be followed (mint4win is not available for Linux Mint 8) http://duncsweb.com/2009/09/27/mint4win-a-wubi-based-installer-of-linux-mint/ Linux Mint 7 Download http://www.linuxmint.com/edition.php?id=38 Linux Mint 7 Gloria User Guide http://www.scribd.com/doc/15884753/Linux-Mint-7-Gloria-User-Guide HowTo create a Linux LiveCD https://help.ubuntu.com/community/BurningIsoHowto Ubuntu 9.10 and Linux Mint 7 can also be run straight from the LiveCD without touching your Hard drive LUg.

What Linux-based Os are you trying to have? To give idea, just visit their homepage then download the Live version of their os. If you can't find waht you've been lookin for, visit this http://www.pendrivelinux.com/

http://partedmagic.com/ This is a very useful OS on a USB stick. Surf the web email reads NTFS partitions.