Hi Eljay

Not sure if you have tried  jajah com, but if you havent it may be worth a try. (Not jahjah as I incorrectly spelt last time). They say you need no downloads. They also give a trial call(not to mobiles though)
This FAQ may be useful
http://www.jajah.com/support/faq/general/#10

You could consider Jajah Direct.

I am a bit confused re Webcalldirect. In the past you needed no downloads , it worked straight from the web. Their instructions  page says no downloads needed, yet they have a download page ! They have a free trial 3 min call (unfortunately not to a mobile) Does it work without a download?

Or are you saying you need XP to use webcall etc straight from the web , even without downloads.

Good luck

Alan