T-Mobile 3G Data Card SMS manager is worse than useless?

I've just installed a T-Mobile 'Walk & Go' 3G Data Card on my laptop.
I was dismayed to learn that the built-in SMS Text feature is so
utterly lame that is doesn't even cause your laptop to make a sound
when a text arrives.

Does anyone know of a 3rd-party SMS client I could download that would
work via my data card, and at least be able to alert me when I get a
text message on it?

TIA.