I purchased a Dyson in 2003 in large part due to their advertising and a box store's employee's "trained" recommendations.  At the time, we only had one dog.  This machine was operating at well less than optimal efficiency in less than two months.  Even with weekly filter and bar cleaning, this vacuum lost suction in a matter of a few minutes.  Couldn't even pick up ordinary lint and thread.  Now, in the fall of 2007, the machine is all but worthless.  We used Dyson's website and even purchased a new filter in 2004 (quite spendy too).  No improvement.  Another note on Dyson's website:  the trouble shooting links assume you can't read the operator's manual or burned it.  Quite insulting with no option to email anyone regarding your problem.

Now that we have two dogs, this product is totally inadequate.  I am at this time researching other vacuums to replace the Dyson.

The bottom line:  if you're looking for the "ultimate" vacuum cleaning, keep looking because this is not it.  High priced for low priced performance.