The key to a decent digital camera is the number of megapixels. The larger the number the better the picture for enlargement purposes, ie 8x10's or 5x7's. But just like any other camera you have to look at what you will be concentrating your picture taking on. For most people that just want to take regular pictures, getting a camera that has at least 1.3 megpixels will be sufficient.
Here's some information you may want to look into before buying a digital camera according to PCWorld:
Picking the right camera for your needs can be a daunting task. To start, ask yourself a few basic questions:
How much are you willing to spend?
A higher price tag gets you more resolution and more features.
How much resolution do you need?
One of the most common misconceptions about digital cameras is that higher in-camera resolution results in better images. For a standard 4-by-6-inch print, there's little difference in image sharpness among 1-, 2-, and 3-megapixel cameras. The differences really start to show when you make enlargements. If you plan to make lots of sharp 8-by-10 prints, you should buy a 3-megapixel camera. Two-megapixel cameras create fine 5-by-7-inch prints and adequate 8-by-10-inch prints.
How much control do you want?
If you're taking simple snapshots, you probably don't need manual focus, manual exposure control, or a bunch of flash settings.
How many shots are you likely to download at a time?
If you're taking just a few shots every time you go out, you can get by with a camera that has a serial-port connection. On the other hand, if you're taking dozens of images at a time, you'll want a camera with a Universal Serial Bus port. You might also consider a SmartMedia or CompactFlash reader that plugs directly in to your PC, which eliminates the need to hook your camera to your PC.
What kind of batteries will you use?
Some cameras use proprietary, rechargeable batteries. Often using lithium-ion chemistry, such batteries typically last fairly long on one charge and are easily recharged. However, they also tend to be expensive. All of the cameras we reviewed for this month's chart use AA batteries, which are easy to find but can become costly if you tend to do a lot of shooting. The best compromise is to use rechargeable AAs and have plenty of them in your bag.
Go Here and see how they ranked the top 5 under $500. It may give you some insight as to some others that are on the market for under $500 also. I use a Sony Mavica that uses regular computer disk and all I have to do is snap the pics than take out the disk and put them in from any computer. I can also preview them on the camera and decide if I want it or want to delete that pic on the spot.