Many companies have turned to temporary agencies to find permanent employees — for good reason. Not only does using a temp allow your company to "try before it buys," but it also allows temps to see if they like your office environment and their job responsibilities before they sign on full-time.
These days, temp agencies are filled with high-quality, well-educated workers — recent graduates, people who have relocated, and those returning to the workforce for the first time in a few years — just the type of people that you want to hire full-time.
Hiring someone on a temporary basis gives you another benefit. You might discover that you don't need someone, or maybe not a full-time employee, to fill the vacant position after all — there really isn't that much work to be done. If you take the time to assess your staffing needs, you may find that you just need to shuffle some job responsibilities or make a different hire in another department.
If you decide to try the "temp-to-perm" hiring method, let the temp know your plan. Most temps will work harder for you if they know their work could lead to a full-time position.
There's only one drawback to hiring a temp as an employee: you'll probably have to pay the temporary staffing agency a finder's fee. That fee could be worth a lot, however — you know you're getting an employee you like.