Great choice on that DR-7!
One thing you should know: The auto level setting feature is for speech recording, not music. If you use that, you WILL be disappointed. There are no good music recordings made with the auto level setting feature. If you need convincing, try recording off your home stereo system and see what the result sounds like.
And I'd recommend that you start saving for your external mics and either a battery box or a preamp that can provide a larger open circuit bias than your DR-7 will provide. I've got a DR-1 and as good as the internal mics are, there is still a noticeable improvement by going with the external mics and the higher mic bias voltage.
For non-critical listening, the internal mics are great. I have friends that use a DR-7 to record their band's practices and the internal mics are good enough for them to hear their own flaws. When they want to record something for other people to hear, they break out the external mics and do it right.