Torn Rubber Boot
 

I just jacked up my 01 S from the rear and noticed the accordion shaped rubber boots just on the inside of both rear wheels are both torn. My car has 39K on it and I'm wanting to find out what kind of problems this creates and how important it is to replace these. Any help will be appreciated!

CV Boots. Not uncommon, but needs to be fixed.

Is this a DIY? Just pull the wheels or do you attack it from the inside? Is the problem that it lets dirt and moisture in?

Here's a link to DIY

Thanks to all for your help!