Good question. We replaced our beautiful and very durable berber carpet with a mid-priced loop carpet from Home Depot. It was not cheap. Within 2 months we had two pulls in the carpet that are quite noticeable. My advice - do not get loop/berber carpet unless it is top of the line and is guaranteed not to pull. Pile carpet is probably easier to buy on the cheap! Also, I would go to a local flooring/carpet company that has been in business for a while. You will get better quality and service (and expert advice) than going with a big chain store. You may pay a little more, but it's worth it in the end should something go wrong.

Firstly there are wool carpets and there are synthetics. Wool carpets will stand up to more wear, hold their colour better and lanolin in the wool resists dirt and stains. Synthetics built up static electricity and actually attract dirt and hold it and are prone to fading quicker. They often show tracking too.

Leisa - I'm not sure whether the grading of carpets is international or not, once wool carpets were graded by the number of tufts to a square inch but now they are based on weight 39 is about the lowest one would go for reasonable quality and around a 55 is average and will give good wear. Check out manufacturers for the most reputable brands - sorry I just don't know what is available in the US.

Laurae mentioned her berber - berber is a beautiful carpet and discreetly mixes many colours which is great for hiding any accidental stains but it is a little hard for my personal preference. It is at the lower end of the weight scale too so is generally less expensive - or should be.

The other issue is underlay - this is very important you get the best you can afford, the better it is the softer your carpet underfoot and the better your carpet will wear. Underlay is usually foam or rubber, I have just had my new carpet laid on the top grade of rubber and am very happy with it but opinion seems to be swinging back to foam as the better option. A lot depends on your climate.

Also ensure you have a top quality and effecient vacuum cleaner and vacuum regularly to prevent grit lodging at the base of the carpet and wearing it by abrasion.