Liz,
To clarify what was said above, PR0 is not necessarily a penalty. Currently Google does not recognize any backlinks to your site which would explain the PR0. The other search engines recognize many but Google is very selective. I have about 1400 links total, a similar number to you but Google only recognizes 16 of them. PR does have an impact if the sites linking to you are also low PR (like most agent sites).
Perhaps the greatest cause for your ranking drop was a destinct algorithm change in Google earlier this year. Many very good sites dropped off the face of the earth while others shot meteorically to the top. No one is really sure why.
Some very simple things to change that will help. Use text links wherever your search tems come up such as "Greater New Bedford, Dartmouth, Fall River" and make sure "real estate" or "homes" is in the link.
Also, It isn't easy to tell what state you work in. Clearly I can tell but people searching for real estate in your area are likely using the state in their search phrase.
An earlier post suggested that the word "links" should be avoided, that is correct.
This tool:
http://www.digitalpoint.com/tools/keywords/ is very helpful for determining your ranking (if any) in Google. There is also a helpful keyword suggestion tool and a forum filled with people far more knowledgable than myself in these matters.
Good Luck!