Hi Ladybrett,
Check out Sevilla5.com - they have listings for short term furnished apartments. For a \"room in an apartment\" you might want to try loquo.com (like Craig's list). Anyway, I think what you're really asking is \"where to live\", right? Well, it really depends on what you're looking to do here and what your preferred mode of transportation is, walking or bus. A lot of students live in the Triana neighborhood which is on the \"other\" side of the river; it's a good place to live because it's safe, has a 'neighborhood feel', and it in easy walking distance to the center and to nightlife. The Alameda de Hercules has a reputation of being a little rougher neighborhood, but I've heard that it's not so bad right now. Santa Cruz is nice, but it's also a popular spot for theft - especially for guiris. If you have any questions about specific areas, let me know and I'd be happy to share what I know or have heard!
Suerte,
Stacy