There once was a statement that 4MP was in the “Professional” range of megapixel. Now compact cameras are 8MP and higher. Professional D-SLR cameras are 10 to 32MP (and some much higher).
Megapixel is all about how much information is in the file. Print is all about how much resolution is in the print data. The printer is the DPI (Dots Per Inch) and this number helps determine how sharp your print is and how large it can be enlarged to. A print of 100x100 DPI is only 100 vertical and 100 horizontal DOTS of ink in 1 inch of print. This is not very much of an image. Now 1200x1200 would be 1200 vertical and 1200 horizontal DOTS of ink in that same inch. That's pretty sharp. DPI is not to be confused with PPI.
PPI (Pixels Per Inch) refers to how many pixels are used in the making of one inch of the image.
If your final print goal is 16x20 and/or 20x26, using a 8MP camera will just get you in there (depending on the distance the print is viewed from). Of course using a D-SLR 8MP camera will give you a better image than a compact 8MP because the sensor on the D-SLR is bigger. But thats a whole other thing...don't get me started on that.
For more information on print resolutions follow this link:
http://www.microsoft.com/windowsxp/...

There can be any number of reasons why this could be happening. A bad cable could be one. Compatibility issue could be another. One of the common problems is an issue on some cameras where there is a corruption on the memory card where it will only read through a Card Reader and not on the camera. When the card is re-formated this usually goes away.
If when you connect the camera to the computer you hear and see some indication that the connection has been established, you should be able to go to “My Computer” and see the addition of another drive. Usually named “Removable Media”. If you don't hear or see an indication that the camera and computer have connected (and the camera is on) than it is probably a bad USB cable. If everything seems to connect and there is no drive icon than it my be a driver issue. Go the the manufactures website and update the driver for that camera model and try again.
A easy solution is a multi card reader. That way you can leave the card reader attached to you computer at all times and don't have to use you camera to upload your photos.
http://www.bestbuy.com/site/olspage...

Very few cameras are not Vista compatible so the list would be rather long. If there is any doubt check the packaging and look for the Vista logo. Some older but still active models may not be Vista friendly and might require are firmware update or patch to work. These can be easily updated online.

I wish it was as simple as saying...”Get this one...it's perfect for beginners”...but I cant do that.
When starting out in the Digital era, it's best for you to look at what needs you have for your “camera to be”.
Do you want small and compact to fit in a pocket and take with you every where? Than a compact or slim line camera is for you and not a Advanced or D-SLR. Do you want to take sports and action photos and want the camera to have a quick response time and expandable? Than a compact would be too slow and frustrating and cannot be expanded to grow with you... so you'll need to look at a D-SLR.
If you have any SLR film experience it will translate over to the D-SLR cameras.

Setting a budget can be helpful....to an extent. High end Compact, Advanced and entry level D-SLR cameras are now only a few dollars away from each other. Making the choice more difficult for beginners. So deciding what type of photography you might want to do will help give you a direction of which camera type to look at.

Cameras need to feel right to You, in Your hand. Go to your nearest BestBuy and try a few at the demo counter. See which one is small or fast enough, easy to understand and feels right in your hand.
Keep in mind that “Point n Shoot” is a feature...not a type of camera. ALL cameras have a full auto mode. Be it a $99 compact to a $5000 Pro D-SLR....they ALL have a full auto mode making them a Point n Shoot.
Hope this helps and you find YOUR camera...digital photography is fun and the possibilities are endless.