Excel 2007 : Constructing a formula that counts distinct words in a single cell

Here is what I need. I need to be able to count text in a single cell without the duplicates being counted. For example a single cell may contain the following:

1, 2, 3, 4, 4, 5, 5

I already have the formula that will count all of the characters an trim the spaces and give me a result of 7.

I need a formula that will do the same thing, but not count the duplicates, giving me a result of 5.

Any help would be greatly appreciated! Thanks in advance!

April