Keep it simple or she won't use it! I would get a receiver and DVD of the same brand for starters so she can use 1 remote. I'm not into the theater in a box deals.
Don't worry about 6.1 or 7.1, find a simple to use 5.1. THX doesn't matter but, make sure it has DPL II (dolby pro-logic 2).
MY BIGGEST GRIPE WITH MOST of the lower priced receivers is the impedances they can drive-BE CAREFUL. Many will say 4 or 6 ohms but if you read carefully, that is only into 2 speakers. Make sure they can handle the impedance into all 5 speakers. I was ready to kill someone at yamaha when I hit this problem. That's another good point for klipsch since they are easy to drive.
My final advice-spend a good buck on the sub. Newbies love to hear/feel the bass. A good sub will also alleviate a lot of the power needs for the main 5 since most of the power used is for bass. A nice 250 klipsch will make up for only having a 60 watt hk receiver by setting the crossover for small speakers and sending all bass (usually below 80hz) to the sub.
What area is she in? You may get some great suggestions for local stores. The big box places usually don't have Denon, Marantz, Sony ES or similar which will all crush similar priced HK or JVC from Circuit City. Just look for yourself-a little denon may have less features and power but will be better built and easier to use.