Format (Underline) Text With A Formula?

I need to underline text which is populated from a formula. How to format numbers, dollars and dates within a formula, but how to underline text.

Desired Result: The employee's who sold more than 100 cars this month are: Alex, Mike and Tim. Please congratulate them on their performance!

Formula being used ="The employee's who sold more than 100 cars this month are: "&cell reference&"Please congratulate them on their performance!"

Current result: The employee's who sold more than 100 cars this month are: Alex Mike Tim Please congratulate them on their performance!

Attempts: I wish underlining text were an option within Format Cells/Custom so I could just use the formula =text(cell reference, "underline"). However, I don't see that as an option in the 2007 or 2010 versions. Is there a way to add "underline text" as my own custom format?

I also tried using "Conditional Formatting" (both "Format cells only that contain" and "Use a formula to determine which cells to format)." I can't quite get it because I don't know how to list names for the former conditional formatting. Vlookup is the only way I know how to refer to a list for the formula based conditional formatting, but this would stop after the first name on the list is found and ignore the rest of them.