For software type business, you might want to start with just learning about adwords in general as it's not technically a local business.
Recent thread on the subject:
[webmasterworld.com...]
Then you need to research some keywords like
plumbing software
plumbing estimator
etc..
etc..
Create an account at adwords and create the ads.
The adwords help pages are really great to get started.
I think your clients best bet is to do some direct marketing. There isn't a whole lot of volume for the above search terms.
A few of my favorites:
Getting started
[adwords.google.com...]
Searchable Help Center
[adwords.google.com...]
AdWords Demos and Guides
[adwords.google.com...]
Optimization Tips
[adwords.google.com...]
Learning Center
[google.com...]
I wish you the best of success with AdWords, pab1953, should your client decide to try it.
AWA
PS - I wanted to mention to the Forum that I'll be away from the office from Friday through Monday. So I'll be back to posting on Tuesday.