louie, got to admit, though, that AJAX, even for tiny thins, really adds a little "sparkle" to a website.
My own opinion on this is; the OP appears to me to not be too comfortable with programming (or he would have mentioned a language, etc), so a non-programming solution would probably be right for him.
Probably something as simple as this would do the trick:
<a href="mailto:subscribe@blah.blah.com?subject=subsc ribe_me">Click Here to subscribe</a>
Yes, the "?subject=" bit is non-standards-based, but (and this is the important bit) it works.