I highly recommend Springfield XD's and XDM, S&W M&P, Ruger SR-9, Ruger 24/7, almost any 1911 from Springfield, S&W, Kimber, Ruger, etc.
You can get a nice, full sized home defense weapon for less than $600.
I highly recommend a small, powerful, preferably an LED flashlight. Surefire makes the G2 and G3 LED's very inexpensively and are very easy to use and will damb near melt the wallpaper of your hallway illuminating the area.
If funds allow, you may want to look into a light / laser combo from Lasermax or the X2 from Insight. That's another $300 or so. If you go that option, you'll have to make sure you get a gun with an accessory rail.
I also recommend you visit a website called
http://www.guntalk.tv/site.php. Tom Gresham, the host of guntalk radio and Personal Defense TV has put together a massive collection of short videos that are very entertaining and extremely educational, especially for a n00b wishing to gain some base level of knowledge before going to a range or a gun shop/ show and asking questions.
There is a small membership fee for that website. If you are on a budget and can't pay for it, please feel free to PM me and we can work something out, I'm sure.
I also recommend against teaching your significant other unless
A: You wish to no longer be significantly others
B: You are a very good at instructing people.
I'd be more than happy to share my experiences with instructing.
