The 35/1.8 is a very good lens, of course if you factor in price, then the 50/1.8 is even better. If you're shooting in very, very low light (like inside a pub or dimly lit restaurant), nothing is going to help you save a D3/3s/700; and a fast f/1.4 like the 24/35/50/85mm f/1.4 lenses. Then you have to ask yourself, is it worth the expense? How many percent of keeper shots do you stand to gain vs. the investment of close to RM8k, if you chose the cheapest option of D700 & 50/1.4. And then there is the issue of too shallow depth of field. Can you accept sharp eyes and blurred noses? Or how about sharp noses and blurred eyes? If you rely on AF in dark places these things happen more often that we wish it would. And those piggy cameras are 2x the weight of your current one. Would you be happy hiking with it? And those lenses... even piggier (if there is such a superlative word) than the cameras.

Now look at "buying" higher ISO. Now, say for instance the D3000@ISO1600 is about the same as D7000@ISO6400. You don't want that much noise. Then you would still use the D7000 at 3200. Or less than that. Remember that ISO6400 is 2x the sensitivity of ISO3200. Imagine you have to pay 2x the price for an increase from ISO400 to ISO800. Would you still consider it? Doesn't sound very attractive anymore, right? Don't be fooled by the big numbers. Essentially you'd be paying more than two times the price of the D3000 just so that you gain one stop or at most 2 stops of light sensitivity. Where is the economy in that?

That said, the D3000 and 35/1.8 I feel is more than sufficient for >90% of the situations you will be in. If there is not enough light, the answer is usually not having a faster lens, or having a higher ISO. The answer is to have more light. Maybe a bounced flash? Or if you're not shooting people, a tripod and slower shutter? Or if you're shooting people, perhaps you could move to somewhere with more light?

Upgrading your body and lens is not the way to go. Changing how you shoot; where you shoot; and paying attention to your light sources, now that makes for better photos. Learn and know your camera's limits, and learn to work within them, thats the reward of photography.

Of course, if money is no object, and a D7000 is pocket change, then by all means, buy it yesterday already.

Pls. help me to check whether my eyes is correct? Is my camera facing a front focus issue? I need to calibrate lens or body focus mechanism? I've no knowledge for this