this might not apply now but, when I first moved to linux I
too tried to use no-ip but I could not get the service to work. I ended
up with Dyndns.org and it has worked for me without trouble.

Two other things:
If you use Opera, there is a widget of dyndns updates that will run for
you.

And if you have a router, I use a linksys wrt 54gl router running ddwrt
software and it has a service feature for using dyndns OR noip.