When buying a digital camera what is more important the pixel size or x300?

300x? if is optical is better if is digital not

The more pixels your camera has the better quality picture it will take.

The higher the pixel count, the sharper the image will be. My old digital camera produces 2 mega pixels. I would recommend a higher rating if you want to make enlargements, but 2 mega pixels will do fine for email and normal snapshots. If you are also concerned about zoom settings, anything that is digital will look like crap. Stick to optical zoom if you want crisp, clear images.

The number of pixels is what is most important. When a camera is described at 5 megapixel, it means that you are getting 5 million pixels per picture quality. A pixel is one dot in a sea of millions of dots that make up the image that you are photographing. So the more pixels, the better.

Digital zoom, i'm assuming by the 300x, is worthless. You can use photoshop or any of the other photo viewers to produce digital zoom.

I'm assuming "x300" is refering to the zoom power rating. Just remember in a camera megapixel is the detail of the picture. Generally 3 megapixel = good 4 x 6 print size, 4 megapixel = good 5 x 7, and 5 megapixel = good 8.5 x 11. Megapixels can be equated. A standard LCD computer monitor is capable of showing a resolution of 1280 x 1024, multiplied is 1.3. That means that this monitor is capable of displaying an entire 1.3 megapixel image. So for computer image purposes short of printing, higher megapixel isn't necessarily better.
Secondly the zoom rating is often an equation. Let's say the camera has a 10x optical zoom and a 30x digital zoom. Some manufacturers will multiply the two to get a total zoom power, in this case 300x zoom. The optical is the only zoom to look for. Optic zoom refers to the ability of the optic lens to zoom in or out, creating a clear zoom. Digital zoom is the same as looking at your computer monitor closer. Is it any larger, yes. But is it clearer, no. Because you are only seeing the small detail of the picture closer, but you are not effectively zooming in on the subject.
So basically it comes down to, how far do you need to get to the action? If close go for more optical zoom. Point and shoot digital cameras offer up to 12x optical zoom, usually with a little bigger size though. Thin cameras offer usually between 3x ~ 4x optical zoom (Kodak is apparently comming out with the first exception offering a 10x zoom and thin size early this summer). As for megapixels, don't go lower than 3, but if you want to crop, or have more room to work with your photos, go with more megapixels for the reasons listed above.

Pixelation is more important as it determines the quality and sharpness of the picture.The zoom is useless as any good photo software can produce digital zoom and zoom into the picture .

pixel size every time,the pros use a thing called the pixel/print quanative ratio.That is that a ppqr of one hundred or above is the minimum accepted quality for printing.The higher the ppqr the better.to work this out you divided the pixel size (say 6Mb)(6,000,000)by 3000 to give you 2000 you then divided this by the sum of the width and height in inches of the print you want (say you want 6 by 4 =20 (6+4+6+4) which gives you a ppqr of 100 so therefore if you want quality 6X4 prints you need at least a 6Mb camera.If you think that a standard A4 sheet is approx 10" X 6" you need at least a 10Mb camera to print to this size.If you are not planning to print then a standard 17" monitor picture will need a 10Mb camera to do the picture justice.

You want a pixel size 4 or higher for sharp photos. Low pixels suffer most in dim light. Zooms are not as necessary with digital since you can enlarge pretty much. Keep in mind that the higher the zoom, the more likely you are to suffer blurring from camera shaking.