There is a huge T-Mobile office in Vienna so there shouldn't be a problem finding a retail store that will sell you a SIM to do what you want. Getting data service on a prepaid plan might be more complicated, if not impossible.
I've used TMo all over Europe with no problems. You might want to check with a local Tmo company store before you leave. Anything that you can buy in the US will be cheaper than if you wait to do it once you get there.
Originally Posted by vox
Is there a carrier with pay as you go in Vienna? I'm about to go there on vacation so I shouldn't use my work SIM. My device is unlocked, so that's not an issue.