Selecting individual items from multi item list box

I've created a multi-list drop down box for one of my tables within a certain section. It's for a product section that I've created. The idea is that by selecting various items in the box, the code will know to display that item throughout various parts of the site where specific types of product are displayed: i.e., Sale, Rent, etc. This way you can have one table for products and then, depending upon which items are selected, the items may appear in one or more areas throughout the site.

My question is this...

Now that I've got the multi-item drop box created and working, what is the php or mysql code that needs to be used to check for the existance of one or more of the items within the various products so that only those records will be selected? I guess I need something like (X list CONTAINS "xxxxx" OR "yyyyy" OR "zzzzz"). You get the idea.

Also, Dave... I noticed that when I create the items for the multi-list box, they are dropped into the actual mysql with both leading and trailing spaces. This makes it so that if you do a simple query for something that equals something else, the record does not show up. I've had to manually go into the table and remove the extra spaces.

Jim