I have to agree with "namedeleted"...a TLR might be an option. Not only would you get much sharper pictures (considering it's medium format film), but depending on the circumstances, it might actually be much less conspicuous. That sounds kind of strange...a big, twin lens camera might be LESS conspicuous. But the thing is that most people have never seen a TLR before. If you're very casual about it and don't draw attention to yourself, the average person probably wouldn't even recognize that it's a camera! The public is so used to seeing people look through a viewfinder (or the LCD display on a digital camera), that when you look through the view screen on TOP of the camera, they probably wouldn't even think that it's a camera.
The closest I came to "street photography" was when I was taking pictures at a lake in the mountains. I was taking pictures with my Yashica A, which is a TLR, as you probably know. I'm mainly interested in landscape photos, so at first I was just taking pictures of the lake. Well I decided to get some pictures of people around the lake...just loading their boats into the water, walking on the trail around the lake, etc. I thought it might be interesting to take some natural, candid pictures of the people. At first, I was kind of nervous because I had never taken candid pictures of people before (well, not strangers anyway). But then I realized that it really wasn't any different than taking pictures of the lake. As long as I didn't bother them, they probably wouldn't even notice me. And they didn't. They didn't notice me at all. The people were completely obvlivious and just went about their business.
I think part of the reason was because I was using a TLR and so when I was looking in the view screen on top, they didn't even realize that it was a camera. I acted very casual and just talked with my friends while I took the pictures.
I'm hardly an expert, because I don't do street photography. But I would think that as long as you don't do anything to draw too much attention to yourself, and as long as you don't bother them, most people probably would never even notice you. Most people have so much on their mind (especially right now) that they are totally oblivious.
By the way, legally you do NOT have to ask permission to take someone's picture if they're on public property (public street, public park, etc). The laws might be different in some countries. But in the US, you don't need to have permission as long as they're on public property and you don't use the pictures for commercial purposes. You'll have to judge whether you can take the picture without the person noticing or without bothering them. Most people won't care or won't even notice. In some cases, it might be better to just introduce yourself and ask the person's permission. But yeah, I can see how that would ruin the "candid" moment of the picture. People act weird when they know a camera is around, even if they try not to. They act goofy, or they just get nervous and they can't help it.
Good luck. I hope someone with more experience can help you. Try posting your question on Photo.net.