If you remember about my first post, i tell about unetbootin, unetbootin is software tools to create live usb. This software is available on Windows and most of linux distro have this software on their repo. You can download here. http://unetbootin.sourceforge.net, And you need usb flash disk with standard windows partition.
If you success installing archlinux, if you want to install unetbootin on archlinux, just type
#pacman -S unetbootin
After you install on linux / windows, now run unetbootin
Run unetbootin as administrator in windows, or as root in linux.
Choose Diskimage then select your linux iso, then choose drive and select your usb flash disk drive, then click OK.
Wait until finish or Installation Complete.
If done click on exit, then reboot to try live USB, don't forget to set your bios to boot from flash disk.
Another way is using "dd" on any linux distribution, this methods will erase data on your flash disk, and partition on flash disk will be resized to suitable for archlinux. Make sure you backup your data on flash disk.
Check your flash disk using fdisk -l
actually if you using laptop, most of fdd will be displayed as /dev/sdb1
To backup & restore
#dd if=/dev/sdb of=/home/user/backup.iso
#dd if=/home/user/backup.iso of=/dev/sdb
To flash iso to flash disk
#dd if=archlinux.iso of=/dev/sdb
Note: /dev/sdb1 --write without any number, so if you see /dev/sdc1 you just need /dev/sdc, etc
Wait until finish.
Then try boot from USB.