proper usage of "regards to" vs. "regard to".

Use "with regard to" when making reference (as within the text of a business letter).

Another option is to just "RE: _______" at the top of the letter/e.mail and separate from the body.

"Regards" has a different meaning, and could be used as a way of ending a business-like correspondence. ("Regards, Lisa") It could also be used as in, "Give my regards to Broadway."

There's also using it as in, "I regard this as a serious matter."

And, just a note (and example) on a somewhat related matter: Regardless of what many people seem to believe, there is no such word as "irregardless".

From this page:

http://web.uvic.ca/wguide/Pages/UsInRegardsTo.html

"Use in regard to, with regard to or as regards. Better still, avoid altogether a phrase that smacks of business-ese and jargon."

I'd simply use "regarding" or "about" (as in "we received three questions regarding the budget" rather than "we received three questions in regard to the budget").

Of course, the other way "regards to" can be used is in the phrase "give my regards to Joe." In this case, it's always regards, not regard.

'Regards to' would generally apply to the giving of an affection OR should I say; in regard to ... Good Bye.