Yes you will have to start over.  Ranking is based on several factors, one being the age of the domain name.

SEO FYI:  If you did a search for "click here" on Google, the Adobe.com web site is #1 (just read this somewhere).  That's because the term "click here" is the most widely used TEXT LINK on the web and Adobe.com has millions of web sites offering their free Acrobat reader by telling people to "click here" to down now.

So this shows that while the domain name is important and enhances your rankings, high rankings can be done in other ways.

I wanted my web site to rank well for the search term, "home for sale in jacksonville florida."  When I trade links with other web sites, my domain name is hyperlinked using the search term AND title "home for sale in jacksonville florida."  I'm on the 1st page on Yahoo (#10) now and my site is about 6 months old (I think!).  I can't master Google.  I've had web sites with a PR5 go to a PR0 in the last 3 weeks, and went from #3 to #345 for a individual search term.  Go figure.  Yahoo is easier :)  You have to optimize each page for each different search term.

The HTML looks like this for my home page site:

<a href="http://www.jacksonvillehomeinfo.net">Homes for sale in Jacksonville Florida</a>  - Homes for sale in Jacksonville Florida.

If you do the same for YOUR web sites when you trade links, it will eventually climb higher on the search engines too!

That is really confusing for a non technical person like myself.  I am printing it to discuss with my Coach Lonn Dugan.

Laurie,

I am not expert here ... just from my experience ... I changed from my old domain name to a new one just last fall ... any rankings I used to have went ... well, down the drain ... but after only about 2 months of working on my site A LOT, the search engines started recognizing the new one and it's doing much better than before. I would say if you want to do it, the sooner the better.

Shoot!  I see the pasted HTML didn't work because of the spaces alloted here.  

Corrected:

<a href="http://www.jacksonvillehomeinfo.net"> Homes for sale in Jacksonville Florida</a>  - Homes for sale in Jacksonville Florida.

Tip: Forward your old domain name to your new one until your new domain ranks in the search engines.