The drawback to this system is that you have to discard the bag when it is full and replace it. The bags aren't particularly expensive, but sometimes manufacturers stop making the size you need. This effectively means it's time to get a new vacuum.

Bagless vacuum cleaners are an outgrowth of the small hand vacuums first made in the 1980s. They use carefully ducted air to deposit all the dust and grime in a catch-container that gets emptied after each use.

These have no disposable bags, so they are more convenient and have a lower total cost of ownership. Additionally, if you accidentally vacuum up the car keys, it is easier to fish them out of the grime.

A drawback to bagless models is that they have separate filters for dust and allergens. These can be fragile and require regular cleaning. In addition, if one of them is destroyed, a replacement can sometimes be pricey.

This is somewhat offset by the fact that an Internet market for parts has sprung up to meet this need. With conventional vacuums, the filtration system is part of the disposable bag.

For bagless vacuums, look at features you'll want, such as a headlight, integrated cleaning kit and built in dusting wands and cleaning nozzles. The industry is moving towards bagless machines for their convenience features (and the lower overhead of making replacement bags); therefore, most of the higher end vacuums are now bagless.

So which models are hot right now?

We have looked at and can recommend the Eureka bagless 4885 Whirlwind SmartVac vacuum cleaner. It is affordably priced and has a powerful 12-amp motor for suction. It also has several attachments to extend your reach, such as a cleaning wand. It's also geared for easy maintenance, with tubes that resist getting clogged. The dirt cup is easy to remove and empty.

For people who live in apartments, Hoover's U5269-900 EmPower Bagless Upright Vacuum has the quietest 12-amp motor of any of the models tested by Consumer Reports, with innovative sound baffling. In side-by-side tests, it's noticeably quieter, though far from being silent.

Like other vacuums in its price range, the Hoover model has the usual array of cleaning wands and attachments. One particularly nice innovation is the rack that holds all the attachments close at hand.

Some of the more innovative models in this product range are the Hoover Z series. These have the ability to fold up in a "Z" configuration, which allows you to maneuver as if it were a canister vacuum for tight quarters, while maintaining the benefits of the suction power that an upright vacuum cleaner has.

It also has supposedly self-cleaning HEPA filters. Since our floor model wasn't in use long enough to test this, all we can report is that the filters didn't become soiled as rapidly as on the other models.

The Z-series vacuums are solidly made. We had concerns that the joints would compromise airflow or might stick as it got reconfigured, but were pleasantly surprised when this did not happen. The other major drawback on the Z series is that it's roughly $500, even though it has the same level of cleaning performance as the other two models listed above.

In conclusion, the bagless vacuum cleaner appears to have transformed the floor care appliance segment. None of the models we looked into had the anemic 9-amp or 6-amp motors used a decade ago. All had a professional grade 12-amp motor. You can't go wrong with bagless vacuums.