As you have Windows 7 installed on your PC, I recommend using the Windows version of unetbootin. So to get OpenSuse onto your USB drive you'll need to do the following: Boot into Windows and login to your desktop.
Download and install the windows version of unetbootin
Download the .iso for the latest version of OpenSuse
Insert your USB drive and format it. You can do this quickly and easily in Windows by opening 'My Computer' and then right clicking on the entry for the USB drive and selecting 'Format...'. NOTE: Ensure it is formatted as FAT32
Run unetbootin to install the OpenSuse .iso onto your USB drive.
NOTE: When you first run unetbootin the 'Distribution' radio button is selected; which allows you to select a version of a distribution, which it will then download. You do not want to use this option because it typically contains download links for outdated versions of the distros it supports. So you need to select the 'Disk Image' Radio button instead.
Here is a screenshot of unetbootin , taken from the unetbootin projects sourceforge page. The screenshot depicts using unetbootin to install Ubuntu 10.10 on a USB drive, using the 'Disk Image' option.
To install Suse onto a USB stick with unetbootin using the 'Disk Image' option: Select the 'Disk Image' radio button in unetbootin
Select 'ISO' in the dropdown box next to the 'Disk Image' radio button
Click the '...' button on the far right, which should pop up a file selection dialog. When the selection dialog pops up, navigate to the Suse .iso you downloaded, select the .iso and hit OK to close the popup.
In the 'Type' dropdown in the bottom left of the main unetbootin window, ensure that 'USB Drive' is selected.
In the 'Drive' dropdown, select the drive letter that windows has assigned for your USB drive. So if your USB drive is 'E:\', then ensure that 'E:\' is selected.
Finally, hit OK in the main unetbootin window and all being well, unetbootin should install the liveCD onto your USB stick.
unetbootin will work for pretty much any Linux live .iso. I've used it many times to install various distros onto bootable USB drives under Linux and Windows with no problems whatsoever.