Sounds like a great combo for your needs. I picked the same combo of lenses with a D5000 3 years ago, and it has worked great for me, although I do want a D7000/7100 or D400 now. I have some fabulous landscape shots with that 18-105mm kit lens, enough that friends and family are constantly telling me I should publish them. I also have some fantastic wildlife shots (including birds, one of my favorite subjects) with that 70-300mm VR.
Some thoughts on your requirements, as mine were almost exactly the same, and again, I purchased almost an identical kit as you are looking at:
1. Picture Quality
- D7000 is going to be great for you, no worries on PQ.
- 70-300 is excellent at 70-250. 300mm is a bit soft, experiment with 'stopping it down' to f8, but it is still an excellent buy for the money, unless you want to step up to at least $1500 for a pro lens.
2. Low-light photography
- a bit to be desired with these lenses, but the D7000 and VR on both lenses will compensate nicely. Again, to go up a level in low light, you need to spend more on your zoom lenses, or perhaps choose a few cheap f/1.8 lenses, I picked up the 35mm f/1.8 for $250, you can't go wrong - it's a *great* lens.
I do a lot of
1. Action photography (Outdoor + Indoor)
- indoor may be a challenge at the longer focal lengths with these lenses, as they drop down to f/5.6 iirc. That's going to bump up your ISO a lot to compensate. In these situations, I chose to pick up an SB-600 flash, again, another $250 to your kit, but in my opinion, was a great addition for low cost. Don't expect to do long-range shots indoors with the 70-300, even with a flash, not the greatest results in my experience, but, to upgrade to be able to do that is a lot of coin.
2. Nature photography (Birds et al)
- outdoor, sunlit days are great, I have a number of bear/mountain goat/moose/elk/bird shots that are terrific, I've got some stellar shots from the Rockies in BC and Florida Birds, as well as lizards and monkeys in Costa Rica. Again, I must stress the use of the 70-300mm at 300mm is a bit lackluster, but it is a great deal for the price, and the 70-250mm performance is still excellent. Eventually, once you realize your limitations with the lens, get a good/cheap monopod, again a little extra money, but you will learn to love it.
- the 18-105mm is useable for portraits, I've got some great shots of my kids (6mo & 2y) with that kit lens, but in a year or two you will start to notice it's limitations, it's not the sharpest lens. Again, the addition of a 35mm 1.8 was ideal for closeup newborn pics (especially in badly lit hospitals), and there are some cheap 1.8 50mm and 85mm DX lenses too.
- I have some excellent landscape shots with that 18-105mm. Buy yourself a tripod and a cable release, again a little extra, but worth the money if you want to get great shots.
Basically, my impression of that kit was: Perfect for starting out, covers all you need. I absolutely loved the combo of lenses.
Later, I picked up some accessories: Tripod for landscape and portrait shots, Monopod for Bird photography, flash for indoor & portrait. (one word of advice, if you pick up both monopod & tripod - get the same quick release heads, I have two different sizes, and am constantly having to switch quick release plates)
After those accessories I also picked up: Cable for the flash to use off-camera for a little more creative portraits, remote for self/family portraits.
Somewhere along the line I also picked up the 35mm f/1.8 DX lens (again, a great price for a beautiful lens) for low-light and creative depth of field shots. I also picked up a 300mm f/4 eventually for birding ($1500 value, used for $750, I got it for a steal).
All in all I've spent about $3500 and I have:
Kenko extension tubes for Macro
To upgrade to anything better is going to be expensive. Upgrading my birding lens was the biggest expense I have done since the kit at the beginning, but again I got it for a steal.
My thoughts going forward:
Upgrade my $500 70-300mm to a $1500 300mm f/4 for birding (done)
Upgrade my $250 18-105mm to a $900 10-24mm for landscapes
Upgrade my $500 D5000 to a $1100 D7000 or $2000? D400
Add 50mm or 85mm lens for portraits
Add 105mm f/2.8 macro lens for macro fun - everyone should have one
You can see any of those options to jump up a level in quality or ability above the kit lenses are quite a jump in cost. The accessories I mentioned are definite helps in the longevity of the kit you have chosen.
EDIT: wow, longwinded, sorry for the wall of text.